2nd walkthrough a couple questions for everyone!

My first playthrough I got all planets to 100%
I have all strike teams at level 20
I got one Ryder up to level 132, the highest level. I even have another Ryder over level 100

Since you enjoy the game, I would do as much as possible.

How do you do it? Lol I am so dead tired after priority and loyalty missions, that I can't even get around to all the other stuff and my first Sara I beat the game with is at level 38 only.

It does cost mission funds, but it also increases their odds of completing missions. That particularly becomes relevant when you start sending your Strike Teams on gold op's.

As mentioned, mission funds only become relevant for the multiplayer where you can use them to purchase equipment from the store for your MP kits. If all you're doing is the campaign use them to beef up your strike teams.

I'm about to start a second playthrough as well, and am planning on only doign the main quests for the planets. I have doen everything but tasks on my first run (can't be bothered with those random encounter tasksà), and some of it was a real grind... SO no I'm only goign to do story-stuff.

1. Side quests are Ok, but I can tell you when I avoided all fetch quests I enjoyed the game much more and maintained a better pace. Examples of quests to skip are the Mineral survey, Plant survey, the Vortex sidequest, Turian ark debris on Havarl, Remnant tech gather quest on Havarl (handed out by one of the sages).
2. Yes Strike teams to level 20 and when you have enough Apex points equip them with Human intelligence. Dump the teams that accumulate too many negative traits as they are not worth it.
3. I do NG+ because I have a number of mods that enhance the experience at the higher levels. Keep in mind with NG+ you cannot research augmentations again, so if you lost any augments because you forgot to deconstruct something and sold it, do not start NG+ with that game.

Some of my personal tips:

1. There are random side quests from the spawns that pop up over the map. These can be fun as you never know if that next spawn will have a clue or not. I loved finishing these on all worlds (Havarl is the only one that does not have it).
2. If you have not done it before, try finishing all the missions on Havarl before going to Voeld. The NPCs there treat you differently
3. If you haven't done this before, take Vetra with you on Eos when you meet Drack the first time at the Monolith with the Kett shields
4. There are lots of little nuggets out there if you take the time to drive around. I found an Angaran saboteur on Kadara living out of a shack fighting off exiles single-handedly. When I came back with Jaal he was able to convince her to leave and go join the resistance. This is an example but these little nuggets of content are what enhance the experience (in my opinion anyways)
5. If you are playing on a PC, there are a lot of mods available now that can enhance the experience. Check out ME mod forum and there is a thread with lots of recommendations. Enjoy.

Hope that helps!

I'm on my second playthrough now as I want to experience the other side of the dialogue tree with a male Ryder and make different choices to the ones I made last time. Also playing as an Adept whereas last time it was an Infiltrator. Obviously different romance too.

I tend to be a completionist. I like the game so I'm happy to go for all the side quests second time around as well.

For my third run through I will probably go NG+ with a higher difficulty level and try some other combat styles but, knowing me, I'll still want to complete as many quests as possible.

I have an NG+ question though. Do you have to keep the same Ryder or can you change looks/gender?

You can change Ryder completely and play the other sibling.  You can also use the character generator during the game in the medbay as well.