I'd recommend Uncanny Avengers before Avengers, IMO. Truth be told, I was kinda unplugged from Hickman's stuff in the beginning and kinda missed the Infinity boat, but I've gone back and read it now and it's good stuff. So, I'd say so, yeah.
That's part of the fun. You can come and go as you like! There's no minimum amount of posts per week or anything, your character would just gain stats slower. I have a full time job, and basically a second full time job with having a 3 year old, I understand time is precious LOL. RP'ing is one of my only vices though, I wouldn't let time restraints be what makes or breaks it for you!
Hey man, any chance you'd be interested in joining the new stat based GLC rpg? I think we've got about a dozen or so players so far, and we're always looking for more people to ring sling with!