Any question answered...

since people are talking clip systems... which are considered to be the most FG/SS friendly?

whilst I like my Crank Brothers egg beaters, I know that they are no good for FG, and I suspect that they may be involoved in my shoes snapping.

Pondering going down the road/3 hole systems, how much better than 2 hole systems (eggbeater/spd's/etc) are they?

Keep the same cleats and get Candy 2s. I swear by them.
I used them on a fixed, FGFS, folder and a road bike. Since I don't race I can't see any benefit in switching to carbon Look Keo and such.