been told both ways, does a higher number add more skid, or more grab?

For every abrasive (sandpaper, Abralon, Siaair, NEAT, Trizact, Scotch-Brite, etc.),
the higher the grit level means the abrasive is finer or smoother than a lower grit level and the ball will go longer and grab the lane later. The lower the number, the rougher the abrasive is and the earlier it will grab the lane.

The area in reference is a square inch.  And of course the higher amount of particles, the smoother it's going to be.  4000 is so smooth it's almost a light polish without specifically using polish, and I really wouldn't go under 1000 unless you're trying to burn a shot in.  But everybody else has it right.  Higher the number, smoother the surface. 

Ok thank you. 

Another question about abralon, what is everybody's personal preference on frequency of using the abralon pads?  Wanna keep the surface as fresh as possible, but not overdo it to kill the ball early.

That's tricky.
I get 3 - 5 uses from a 4000 grit pad, but that's not with full pressure. 4000 is very fine. Duller ones will get a little more, maybe 4 full pressure, full ball uses.

As for the ball, it depends on too many factors: lane surface, rev rate, actual surface (500/2000, 500/1000/2000, 500/4000, 500/1000/2000/4000, 1000, ...)
I'd do a light refresh (usually by hand with a damp pad) at least once every 9 - 15 games. The finer the surface, the more often I'd do it. The higher the rev rate, the more often I'd do it. Until you need a full resurface to build up the Ra again, you're not going to be removing a lot of resin.

With polished balls, I'd just keep a sharp eye on the finish, but around 20 - 25 games, depending on the rev rate and lane surface roughness.