{Trostani's Summoner} is played, then {Eyes in the Skies} follows. When I put my 2/2, 3/3, and 4/4 out and then also put out my 1/1 bird and then populate, what would I populate?
Each token, or just one of my choosing?
Populate: put a token on the battlefield that's a copy of a creature token you control.
So, only one.
But when I play Eyes in the Skies, and populate comes in, would I populate just the 1/1 or can I populate my 4/4 that's already there?
you can populate any creature token you have.
You can populate the 4/4, if you had an 8/8 you can chose that. It's your call.
701.27a (http://imtgapp.com/forum/index.php?action=imtg;area=rule;number=701.27a): To populate means to choose a creature token you control and put a token onto the battlefield that's a copy of that creature token.
The rule
Note that you choose the token not target, so even if your token has shroud it can be populated