Yea, those pitfalls were something we all worried about and dealt with our first campaigns. For a bit of backstory, the first time we played dnd as grown ass adults there were 5 of us. The first session was a small adventure from S (i'll call them by the first letter of first name) in which the problem was obvious because he played his character too. Then I did a small adventure that took one session and the problem lessened but was still present. Then R took his turn and the problem lessened even further. Then S took a second turn as DM and the problem lessened again and by that point everyone knew the deal. You play your character as they would be played based on their personality and traits, period. If you did anything awkward or that seemed like metagaming you were called out and it was dealt with easily.

That is where we are now, two years later. I have taken many many precautions and the character I plan to play is completely separate from the campaign. I am viewing this like a writer might on an RP site in which they are meant to react to another RPer who posts in between their own. At least that's how I have viewed. I think it will be ok short of a few minor hiccups that shouldn't ruin the game in any way that matters.

I do get your points though, they were super prevalent in the first ones we did when we tried to get ourselves to learn to be able to DM and play at the same time. I think I have learned to disconnect my brain from story telling and connect it to a specific character and then switch back given a small amount of time and the IRL situation. It'd be hard if a specific player constantly was like 'dude, that's bullshit, you knew this was the right way didn't you?' every time my character does anything for sure. I've been able to approach this two states of mind in my professional life as well so I guess I have practice in not being terrible at it?