Milky Way Natives Fighting Each Other in Androma

Well since a Female Krogan is one of the lead engineers of the Nexus I'm pretty sure she is the reason why there are Krogans aboard. Good move by Bioware though I love the Krogan there needed to be a real reason for the Krogans to tag along.

... why?

IMO, a female Krogan engineer makes perfect sense: since they live in separate camps with children, in Tuchanka a clan without engineer would be a dead clan very soon (at least knowledge of redundancies would come in handy in the Nexus, methinks) - not to mention that if she's going to be "on-call" for the entire duration of the journey, 600 years is plenty of time to learn everything there's to know about the ship. Also, since our knowledge on female Krogan clans is very limited, I don't understand how this could be particularly lore-breaking. And finally: I fail to see how she wouldn't be knowledgeable enough to take on the job - Tuchanka is a demilitarized zone, but they do have access to tech and knowledge, as you can find out if you talk to the Krogan scientist on Tuchanka in ME2.

Yes. Because we know for a fact that's all a female engineer in Tuchanka would do. /s

I'm saying that, for all the lore tells us, the female Krogan clans could be constructing a fucking high-tech cloning and genetics laboratory from scrap-metal in Tuchanka, because almost all the lore on female clans is based on the discussions we've had with ONE female Krogan, who was a shaman - and who, BTW, was talking about the importance of peaceful cooperation. The thing is, we know fuck all about the female Krogan clans, but we DO know they live on a planet where engineering and ingenuity is absolutely vital. Also, off-world Krogan have been known to work in technical fields (like Charr, your friendly transport technician).

If anything, I find it more in keeping with the lore than that some fucking human became the lead engineer of Nexus, since the species in general has been capable of FTL-travel for less than 50 years.

So no, I don't think its impossible, or lore-breaking, or whatever. What it is is interesting: I already want to know how she became involved and what made her want to make the journey, where did she get her expertise etc.

We already know that something happened to the golden planets during the 600 years of journey, this is such of an uninformed assumption to make.

It does make me question how long the Arks have been in Andromeda before all this revolution started. I can definitely understand the arguments for this sort of thing to happen, but I was picturing at least ten years before it became practical to have such significant schisms. The rebel base we saw in the gameplay trailer especially made me scratch my head, how long would that take to set up? I don't think the timeframes are going to be realistic.

Looking for logic in how Andromeda is set up is a lost cause from the very concept, but this particular issue you mentioned is not that problematic. We know the Nexus was send before the Arks (it makes sense from universe building perspective) so all you had to do is say it travalled a bit faster than the Arks, so it arrived some years before. 

I think it's fair to say that in-game the Initiative made some miscalculation. Which might be one of the reason behind the outlaws faction.
On the topic of the planet, there were mentions Habitat 7 is different from what they expected. The last trailer might have made some hint about it as well.

Hyperion is likely months to years late.
Though I don't know if the various hubs we'll visit will be made by the MW species or some native species. 

If you and your neighbour end up in the middle of amazonian jungle surrounded by wild tribesmen he'll feel like the closest relative to you. Unificated forced by common threat is quite natural thing. If we try to give some credit on Bioware writing believable scenario - there shouldn't be any imminent danger on Nexus' arrival, so colonists would have enough time for squarrels with each other.
Even with that in mind I'd still fire Nexus government for letting things go so far, that's a combination of weak political will and strong incompetence. 

The Ancient Krogan had already mastered industrialisation and entered the nuclear age 4000 years ago, when conflicts over dwindling resources lead to a nuclear war that blew them right back into the Stone Age. They had to struggle to survive the radiation and the nuclear winter that persisted until the Salarians arrived two thousands years later and "uplifted" them, giving them access to advanced technology once more.

(In fact, if they'd achieved spaceflight and avoided nuclear war, they could have reached the Citadel over 1400 years before the Asari.)

During the Krogan rebellions, Krogan scientists on Rothla managed some kind of exotic weapon (no-one knows precisely what it was) that accidentally shattered the planet into a field of debris. Scientists studying the event by travelling to the edge of it's light-cone report a moment of extreme gravitational lensing around the planet before it was destroyed.

In ME2, we discover that Warlord Okeer was able to use his advanced knowledge of cloning and genetic engineering to create a "perfect specimen" in Grunt, intending to create race of Krogan ubermensch who would thrive despite the genophage.

Suffice to say, the Krogan have proven they can be extremely smart and resourceful, they only need be given a toolbox.

We've seen a number of smart krogan over the course of the series.  The thing is, most of them turn their intellect towards warfare or weapon designs (since that's pretty much the krogan way)  

Those that turn their brains towards less violent pursuits are generally looked down upon.

Well, atm we have a data point of one for krogan females