My First Glock

I've finally got on board, and picked up my first Glock today. I bought a brand new Glock 17, gen 4, solid gray (frame and slide). I bought it from an individual who owned it for a week, during which time he switched the factory sights for Trijicon night sights. He also put on s grip plug, extended slide lock, and Talon granulate grips. All original parts included, case and 3 mags as well. I paid $550, which I think is a pretty good deal, gun looks pretty sweet.
My questions, being new to...

My First Glock