Best approach is to just rent and play for a bit first until you get a sense of what you like in terms of feel and what style you play. Kinda like cooking knives in that regard: get in some "use time" first to find out what you like and don't like.
Paintball equipment gets pricey and there's a lot out there that, I think, is a total waste of money. For the paintgun, performance comes down to just a few things:
- Does it feel good to you? Do you naturally aim it where you want it to go? (That "pointability" factor determined by weight/bulk, balance, grip type and angle, tank position...)
- Is your gas system consistent? And is your paintgun optimized for that gas? (Chances are that last question is not important at all... it is a consideration mainly for older paintguns)
- Do you have a good barrel that is a good boresize for the paint that you use and is finished nice and consistent inside?
That first one is the most important, and you won't know it until you get in some time with at least one or two setups. Then, after that, it's what you and your body are used to. Just like with a knife that you really know, you want to get to the point where the paintgun is like an extension of you and you can do what you need to do without really thinking about it.
For your mask... go with what feels good on your face. Try them on without the strap first to see if the curve is right for your head and face shape. If it is, then put the strap over, adjust and shake your head around a bit. It should stay put without squeezing your head or pinching anywhere. If nothing else, I'd suggest getting your own masks first even before you buy the rest of the gear. If you're comfortable with your mask and you can see without it fogging up and it doesn't stink like someone else's sweat... you'll feel better and play better.
Gloves and padding are optional... unless your wife, like mine, hates seeing bruises all over even if I say (truthfully!) that they don't hurt.
Oh... one last thing that is among the most important. Wear a cup. Soft cup is good enough and more comfortable than a hard one, but you will be very glad that you guys are using 'em at some point, sooner or later. Sooner if you play aggressively and up-close.