#2
There was a (closed) discussion about this:
https://www.ultimate-guitar.com/forum/showthread.php?t=285250

Synthesia might work for tab-ish representation, as can a few other things.

Really, though, you're much better off learning to read sheet music and note names/positions with piano.
#3
Megachords had really useful piano options but they underwent some changes and now they don't work. Maybe they'll fix it?