The SLG is an incredible starter marker, it's perfect for a newcomer to tournie ball and mine did me well all of last year. You definately don't need to worry about the SLG, the tank will also do you fine for a good while, so no worries there either.
The eyes detect when there's a ball in the breach, and doesn't let the marker shoot if there isn't. So yeah, lazers in the barrel is a fine enough description. They just make sure that you're not firing half a ball at somebody.
The weakest link there is definately the loader. It's great if you're only going to be firing upto 8bps on semi, but if you're enterng tournies you'll want something that feeds a little faster and more consistently, especially if you're entering tournies that use ramping. You could go for an Empire ReloaderII if you're on a budget, or a secondhand ReloaderB or Halo (£30) if you want to spend a bit more on something that last you into serious play.
If you're planning on reselling the mask then it's fine, you probably won't get a lot for it though. Masks are the kind of thing worth spending the money on, they'll need to be comfortable and you'll need to be able to see. Worry about that next payday though.
Also try to factor in some decent arm/knee pads. When you're throwing yourself around on a field it's kinda important you don't get hurt too bad, it'll also make things more comfortable when you're reballing in the gym, which I think you guys do.
If you don't mind me asking, I thought that the UWE team had bought a couple of PMR10's to lend out?
Don't worry about asking questions, it's one of the only ways to learn and there's always someone on here to help. Welcome to p8ntballer