Avengers spoilers

My problem with Thanos coming in at the end of Avengers Ultron to say he's going after the Infinity Gems is that if he had wanted them he would have been better off doing it differently.  When the Chitterthings were invading, that was at the behest of Loki, holding his sceptre.  Thanos was allied with the Chits. That is to say, he could have got to Loki more or less directly - "Let's have a strategy meeting, does Wednesday work for you" - hit him over the head with a twobefour, and taken the gem out of the sceptre directly without a lot of irrelevant invasion.
Oh, and Quicksilver being shot makes no sense; he's faster than that. Yes, I know about the Sony XMen issues, but even so.