He never leaves that damn bench by the shop which means I can't pick the lock on the gate...any advice on how to get him to go home??

stealthboy

My sneak is at 80 and he doesn't even notice me. Position yourself so the vendor booth blocks his line of sight. Doing at night helps too. Or, as already noted: stealthboy it.

I went with the stealth boy approach, had one stashed away in Novac when i looked.

He's usually in his house late in the night for me.

I sat within scope range of him waiting for 1hr at a time for 36 hrs and the little [insert profanity] didn't move hehe. Still, all over now

You are going to require a stealth boy to go undetected because it requires you to download data from a terminal that is in the same room with 3 other people..

It is possible to do it without a stealthboy. The first time I went in with a sneak skill of 51, no stealthboy. my alert staus did reach caution, but never got past that, unfortunately when returning with the information I was told that they were aware of the theft and could not use the info any time soon (I reloaded after that). If my sneak skill were higher I suspect it would have been entirely possible to do without a stealthboy and not be detected at all.

If you wait until about 4am the gunsmiths are no longer in the room with the terminal in.

This. They go to bed some time during the night. The guard also never seems to leave the other room, so there's free access.