Whedon should keep EVERYTHING from TWS.
Most importantly:
1- the stunt team!! because actions scenes with characters like Cap, BW, Hawkeye, or any other character that can´t turn into flying CGI, should look exactly as they did in TWS.
2- the edting team, because their job was good
3- the CGI team, because things didn´t look cartoonish, but very real and that it always good.
j/k but seriously I think alot of stuff is being shot on closed sets.