Questions about frame data

I cannot seem to grasp this probably simple concept.

In the columns for character frame data it looks like this.

EXE= the amount of frames it takes to execute this move to the point where it is blocked or hits.

ACT= I don't know what this means and I never saw it in the frames guide.

TOT=the total amount of frames? How do you get to this number?
I can't figure it out.....

GRD=the amount of frames you are at an advantage or disadvantage after a move is blocked.

HIT=the amount of frames you are at an advantage or disadvantage after a move hits.

MC=the amount of frames you are at an advantage or disadvantage after a move counters another move. I assume a counter is a move that interupts another persons attack, during the attack, and only at this point?

Thanks for your help.....

 

Totally out of curiosity, for moves with multiple hit frames, anyone know what frame the grd / hit / mc frames given in the black book are measured from?

I.e. I assume the engine doesnt magically change execution times to make stun end at the same time regardless of whether you hit on the first hit frame or the seventh.