3)I don't think there are at all, I admit C2's sprite editor is quite primitive, I think it is designed only for minor modifications of images, you'd better off using a picture editing software then import inside C2.
Well, a good game maker software (which c2 poorly tries to be) should have a decent image/sprite editor (with functional at least similar to paint.net)
4) you can interact with tiles in events, so it should be possible (didn't try it myself though).
like, how do i make on collision event to break one tile (see super mario bros)?
5)There is no other exe exporter than node-webkit, since C2 isn't created with the code of construct classic, and uses HTML5 based exports.
well, too bad. Just because html5 won't stay for a long time, but EXE games are forever (steam, anyone?)
<font size="1">p.s. this forum engine sucks (it keeps throwing timeouts while editing/ replying to the damn post, also post reply form is wierd and broken)</font>