I completely agree with what the OP said with regards to Aguero - His overall play is still very good, he still looks sharp on the pitch but he is tending to hold on to the ball a lot longer and snatch at shooting opportunities. Like you said, he's trying too hard to find goalscoring form.
With regards to Yaya, we simply have no one else like him. He might not always be the most effective and look unfit, but he is crutial to us. He is powerful, he can pass, he can shoot, he can control a game but on top of all of that - He is a winner, his return will benefit us no end. (Especially considering how bad Milner was against Villa)
With regards to our away form, we simply seem to have lost the belief we had at the start of the season. I really hope this doesn't carry over into our home form, (which it can do as poor away performances add more pressure on home games) as the last thing we need now is a silly draw at home against a side that isn't Chelsea or United - This is one of my main concerns with regards to our run-in.
@Mancio - your point about beating the likes of Stoke and Everton easily at home, but not getting the same result away is purely down to the mentality of the teams and fans going into the game.
City V Stoke - Stoke go into the game with the thought process of "lets try and hold on and hope for a draw" but really they know they're going to lose. They have a small amount of fans at the ground as they are the away team, who also thoroughly expect their team to lose. City and our fans go into the game expecting a convincing victory and nothing less - The atmosphere will also help.
Stoke V City - Stoke go into the game with a "fuck it, we've got nothing to lose" attitude, they will get fired up and try to cause an upset. They will use their smaller pitch to their advantage and the most important point - The atmosphere at Stoke is always good. They will cheer every throw-in and corner as if its a goal and really boost their team. Whereas City will go into the game slightly underprepared (I still don't think Mancini realises that certain teams like Stoke and Everton see us as a cup final at home and significantly raise their game and create an atmosphere) and we only have a small following as we are the away team.
I can guarantee you now, that Stoke V City will be a draw at best for us. A lot of us City fans know how tough Stoke away is and know what City are like in those kind of games. (see recent record in away games against Stoke, Everton, Sunderland and Wolves). It's all down to the mentality of the 2 teams and the 2 sets of fans.
... (and yes, the ref's are more than willing to fuck us over when we're playing away as there isn't 45,000 blues there to get on their back. Ref's in this league are cowards and will cave in to the pressure of home support)