You definitely do not need to choose a specific role. There are rarely, if not ever, roles that require a player to have a special load out. You do need to choose a base colour though, get both a set of green based camo and tan base camo. The vest and other gear do not matter for colour.
What you will need.
1-3 is pretty much the minimum to play small games, beyond that is the extra stuff needed for the more serious games.
Yout will need properly rates glasses or full seal goggles. Do not use mesh goggles, you will not be able to use them at most games.
You will find that most people do not run facepro at all. I personally just wear shooting glasses unless I find myself in a very tight quarters field where I would feel safer with full seal.
Get a good pair of foots with ankle support! Just as important as eyepro.
If you like your fingers, get gloves too.
2. Rifle and ancillaries
Most here will suggest you start in the $400+ range for a rifle. Lower cost rifles will likely break earlier and cost you more to fix.
Of course no matter the cost of a rifle it will eventually break, its when that matters, and for a new guy that only has 1 rifle, you want it to last for a long time.
The wall chargers that come with rifles are crap - don't ever use them. Get a smart charger such as the "Universal Smart Charger" (google it) to start, or jump right into an ImaxB6 or similar.
Get mags that don't rattle - HiCaps are bad, and actually do feel bad. Pick up 6 or so mid caps for your rifle.
Choosing your rifle is up to you. Find a design you like, then research the fuck out of it to find what brand of one to buy. It is ok to come to us with the question of what brand of XX style gun to buy, but don't ask us to compare say an M4 to a Scar, that kind of shit is up to YOU.
3. Basic Gear
Get a vest to carry mags and water in. It does not need to be some crazy expensive plate carrier or super navy seal rig. Find a design you like and try it out.
I have a lot of expensive kit, rifles, and gadgets, but I still run a $20 chest rig to hold mags and my radio. It works, fits well, and has stayed in one piece since I got it used 3 years ago.
Make sure you have the ability to carry water on the field with you.
4. The more expensive gear
Once you have your basic set up that will allow you to play games you can move onto the nicer, more expensive stuff that you will need for the big games.
-Radio - do not get a blister pack radio - there are plenty of threads on here that can guide you to what radio to get.
-Headset - Its up to you what to get, but keep in mind that you get what you pay for, and they do break, often. Do not be that dick that leaves his radio on speaker :P
5. Just fucking showing off, but useful shit
-Nightvision + IR lasers