Why in the prologue people are astonished by "floating rocks"? Why do they point it out?

1. No, you didn't. It was explained to you multiple times. Ryder passed out because a human will asphyxiate quickly, within seconds, while breathing air compositions that do not contain enough oxygen. Pure, simple, that is EXACTLY why.

2. Sam would alleviate certain symptoms given the control he has over his host's body. Alec performed well in the fight leading up to this because of SAM. Disconnecting SAM gives potential for complications in the way a man without a crutch would have issues walking without one. Ryder jr nearly died because he was cut off from SAM forcibly, and he had a UNIQUE connection to his father's (much more advanced than other SAMS) SAM. Alec passing control to Ryder, and having the connection severed, are not the same thing.

3. 200 is an extreme, 150 is the average, and when comparing expiration between two subjects (Alec and Ryder jr.) The younger of the two stands a better chance at survival with oxygen deprivation. (Accelerated by breathing air with no oxygen). This accounts just fine for the difference in their longevity in the oxygen deprived environment.

4. SAM, again if still connected to Alec could have slowed his heart rate to improve his chances of survival. Considering that part of the reason Ryder jr had complications and technically died is because of the botched transfer.... Is a plot hole that could use further explanation. It could be explained by character quirks, a father's worry, etc.... If you'd like to focus on something, focus there.

To summarize: Space magic or not, BREATHING an air composition such as HAB7's will absolutely kill you within seconds to under a minute. Just like if you walked into an unventilated room full of it. (Given the story they were trying to tell, possibly WHY they chose that makeup for Hab7's atmosphere.)

1. No not that. I already figured out why Ryder passed out. The issue was with Alec doing so. What I mean is that I figured out it was him losing SAM that did it.
2.dude, Ryder and SAM's connect is only unquestionably because of the upgrades Alec did. Alec would have these upgrade as well being he is the one who made them. Why would he not have them? Also, the twin has this connection as well.
3.Agien. it matter not being that in ME 30 and 60 health wise has no difference and that is stated in lore. If 150 to 200 is the new max of human life 60 is not going to be considered old anymore.
4.I did not even point that out. I just said Alec passed out because he transfered SAM.
5.I did not say that it would not kill a person. I just said gas exchange is need first for a person to faint from that. Point is mute being the the SAM transfer is what cause him to pass out anyway.

Not really. The Scourge gets away with it being an obvious part of the scene setting at that point, and for me manages to fit in the gap between being realistically explicable and too much nonsense even for ME (and even hard science fiction, not that this is, can have a few far-fetched things thrown in as part of its universe-building). If you've got something like that then it not being detectable unless you know exactly what to look for, especially when we later found out it was a weapon, is reasonable. I think the plot hole there is that the Nexus should've been able to warn the Arks about it, disrupted communications from the Scourge feels like it's stretching things a bit.

The helmet part for the reasons that have been explained often enough. I'd assumed Alec was planning on swapping helmets but saw that wasn't an option since Ryder was passing out anyway. Overall I rather liked the opening of the game. The shuttle ride in (before it broke) is, IIRC, the first time we've seen a space-to-atmosphere transition from the characters' perspective, I liked that.

1. No i mean each race from different MW planets (having evolved differently, with varying gravity) each chose a different golden world based on scans of Andromeda (pre teraform, though teraforming doesn't affect gravity....) Yet they all (aside from the broken turian choice) have the SAME gravity in gameplay.

2. Jack and Kaiden (powerful biotics) have asides if you decide to be a biotic.

3. SAM is capable of translating, but he's not the "traslators" they refer to. Everyone everywhere has them. That was a weird response from you, my point was they went instantly from being unable to understand the Angara in one scene, to conversing with them effortlessly. SAM or not, how do the Angara speak in their native tongue at will? They do it all the time, telling you their words for things. 

4. The brain may not be wired for it, BUT SAM is. He records thought and memories and can communicate just fine without actually being "heard." There's no reason for Ryder to speak out loud to him.

You could say the same in the original trilogy, for either bringing the Normandy in to do a bit of blasting (it gets brought up and dismissed a couple of times, and ignored the rest), and similar with most of the enemies Shepard fights, particularly the geth (geth dropships seem common enough).

I COULD, but the original ME is more mission based, as in: Shep went in, and the enemy didn't use air power THAT time because reason X, and then Shep left and didn't return. But, yes, the Geth drops ships on ME1 planets is an obvious parallel.

In MEA, where Ryder can repeatedly return to the same area or just roam, with enemies replenishing the same bases over and over again, the mechanic just becomes more and more absurd.

Look at it this way - the Initiative isn't the only outfit to not arm their scout ships.

are you kidding me? Shepard had to fight multiple airships in ME and Kia Lang used one to help him successes in a mission. And me3 was nothing but the reaper showing how superior their air support was. They were bombarding troops to the ground from space with giant flying bug things dropping bombs All over the place. And me2 had giant flyING space crabs and fly drones in both me1 and 2.
Yet Shepard still was not constantly bombarded from the air even though the enemy easily could of.

For sure. Look, there's SOME explanation for the Kett.

To me though, it looks like there was a much different idea for these worlds (especially Voeld), with a harsh landscape and hidden Angara civilization, and a designer decided wildlife and Remnant was too boring, and more random Kett bases was the solution.

1. He is breathing the air. Just like anyone else. There is literally no difference in passing out from walking into an enclosed space with no oxygen. The effect can happen in under a minute, well under a minute, in seconds even. I do not understand how you do not get this. You have absolutely nothing to dispute this with, and I posted an article on this already. If you are breathing air, with no oxygen, you will absolutely pass out in seconds, with no need for inclusions from other factors.

2. The link that Ryder Jr. and SAM share is ABSOLUTELY unique. That's not up for debate. This is explained IN-GAME the moment you wake up from the events on Habitat 7, so if you take issue with that you are EXACTLY wrong. Alec and SAM were not connected on the in depth level that Ryder Jr and SAM are. Its their exact unique bond that makes them inseperable/dependant. This is also explained in game.  There are also examples. For instance: Upon crash landing on Habitat 7 the QEC link between SAM node and the landing party is completely severed; Alec Ryder suffered no ill effects from this. SAM can control Alec's bio functions (profiles) but Alec is most DEFINITELY not dependant on SAM. Nothing in the game suggests he would be, and all references otherwise are SPECIFIC to Ryder Jr and SAM's unique connection.

3. Peak health or not (and enhanced how exactly? He's not a super soldier. His enhancements are SAM's influence only. He didn't have them at his time of death, and without them he's not impaired, just normal. I posted a crutch allegory for this earlier) the comparison is between two subjects. The constant is the atmosphere. The only difference between them is their age. You say it can't possibly be a factor, but that's exactly wrong. It's a thing that would most definitely be taken into consideration when comparing how long each of them were able to survive without oxygen.