[1] not sure I understand what you mean here.
[2] I think the UI does need some work in this area, particularly where people can try and build on an unbuildable tile and end up clicking somewhere else. Visually they are addressing some of that, but I think there is room to experiment with how you place buildings your suggestion isn't bag they could also do drag and drop.
[3] I'm not sure a favourites tab would add much but maybe build plans for governers that you can assing to a planet, is it my imagination or did they add those to GC2 in the end.