I think Aguero is a good choice as MC have an 'easy' run of games coming up and he is their first choice striker. I also think it is likely that his price will rise as people start piling in (his ownership has dropped considerably since the start of the season due to the injury). Over the next four games I'd expect him to get a minimum of 4 goals or assists and rise in value by at least £0.3m. That said, I certainly wouldn't bet on him starting every game and if you are only doing it as a temporary move while waiting for Berbatov to return I wouldn't bother, as I can't see him missing more than two gameweeks at most.
Depends on budget and the impact elsewhere in the team of course, the likes of Crouch, Fletcher, Defoe etc are all under £8m and have 4+ goals under their belt already. They might free up cash to develop other areas of the team.
Personally if I was choosing a team with no constraints he would be in it, but I don't have the luxury of being able to make that type of transfer right now due to needing to replace Federici who is injured/dropped.
As for my team probably the biggest concern beyond that is what is going to happen with Lescott, he's been benched in two games already this season as for some reason Mancini has it in his head that can't play in a back 3.