"gaining blocks" - poor choice of words given that there's the standard "making points".
1) I'd do the double-tap. If hit there's every chance of making a nice anchor with the blots on 5 and 4 so it wouldn't be a total disaster. GnuBg says .. double-tap for best move. It says to hit one of the blots with the next 3 choices and making the 2-point is only 5th and a blunder! (-.100) The hitting priority doesn't surprise me because tapping a naughty blot sharply on the nose is the thing to do at the beginning but I'm surprised that making the point is considered blunderful. I guess another part of that is because the blocking effect has been lost given that the point is behind the escaping backrunners. A kind of bolting the stable door thing.
2) Striking opening examples where non-cube (or rather non-gammon) is different from cube. Hmmm. I can't think of anything striking offhand. I tend to play gammonish anyway and have to remind myself not to.