I don't have an answer for number one, but for number two - I think Mech Acuity will be an option, yes. Move a ton of CP into penetration and get additional pen from your offhand trait and it's a viable solution.
Although, still not as good as meta Advancing. t3hasian did a video test on it yesterday, actually.
I don't have any real data to answer your question, but I do have anecdotal experience. I use the AS 2H in PvP, and when I hit someone in execute range while fighting in a close group, it's almost always following an incap, and after the 1-2 follow up executes, my ulti is right back. It seems like it might be generated more by hitting more people.