Maybe before Loki tires to betray him, but after that, he probably wouldn’t trust an Asgardian again.

I don’t think so. Hela wanted to conquer the universe, not “balance” it. Also, she’s smart enough to know that Thanos’s Snap would have a fifty-fifty chance of killing her, so she would probably actively oppose him just to prevent that from happening. If anything, Hela would likely try to steal the Infinity Stones from Thanos if she was still around during Infinity War

I think hela would try smashing Thor’s brain instead hahahaha

Hela can summon dead so everyone vanished could join her army. It's just unknown if dead is counted as population Thanos was cutting to half.

Well not exactly, she has to have the body to resurrect it, I don’t think she or any necromancer (according to Agatha) could’ve brought anyone back if they were snapped