The card states you can perform a boost action after performing a 2-4 maneuver. Does that eat up his action for that turn or can he do a SECOND action during the action phase? (obviously, it couldn't be a second boost and assuming he isn't stressed)

For instance: Snap does a 4 straight and performs his ability of boosting after doing such a move. Can he then target lock, focus or repair a damage card?

Yes he can.

Thanks! Had a game the other day and I was told that he couldn't by my opponent... but they "let" me do it anyway and basically said if I won (I did) it wouldn't really count for my store win record (which, in all honesty, means nothing and is more for petty bragging rights... I hate it), but it's good to know the guy was just being a total jerk about it and that I wasn't playing wrong.

If you really want to rub it into the guy. Run Snap with composure. He can intentionally fail his boost. (Boosting to bump or hit an obstacle) Get a focus action instead from composure and then get his actual action to target lock for a double mod attack.

Composure Snap is a baller.

Well then... this is something I'm gonna have to try!

Not action given make you loose your Action Step except if specified on the card that you loose your action step... there is no blind generic rule that say you have only ONE action for all the turn

...did the guy think the ability used up his Perform Action step?

If that was the case, Wexley wouldn't have a pilot ability at all, because the T-70 already has a native boost.

I am trying to get my head around why someone would think it worked that way

I agree with @Maui.

What was this guy thinking?

And why would this "boost" be Snaps special pilot skill at all? Since every T-70 can boost, Snap would have no benefit from his special skill.

I certainly would not want to play against this guy. No fun.

Yeah, no one really likes playing him. He's a store drifter... annoys the **** out of entire player base of a game at one store, then moves on to another to continue the cycle. The Magic and Yu-Gi-Oh players have outright shunned him from their part of this store... and they were shunned from the miniature players to the back section of the store >_>