HK USP .40 Compact question...

[GPIA7R]

I've got an HK USP 40 Compact here, and I've watched a few videos about it online... reviews, walkthroughs, etc.

I've got a couple of concerns, though, that hopefully you may be able to shed some light on.

First, the slide feels hard to pull back... like it takes more effort than what it seems in the videos. It's not that it's rubbing against anything or has more resistance... it's moreso like the spring is overly strong. I don't have anything to compare it to, but I was curious about that...

Second, when the slide IS locked back... the barrel moves a little? Is that normal? I can jiggle it slightly. Can almost push it in and out about half a millimeter, and very slightly jiggle side-to-side, making noise as it touches the edges. Should it be able to move that much, is that a safety hazard, or is that normal?

Thirdly, when field stripping... when I go to put the spring/recoil back in, it doesn't look like there's a perfect way to do it, y'know? It places in, and stays, but doesn't quite look natural... probably looking too far into that one.

Lastly, how often and how should I maintain it? Is there a specific sort of oil or something I need to apply? When, and where?

Thanks!