integrated kneepads might not work out for you, it's one of those one size fits all in terms of proportions. If you find a pair of knee pads that work really well, you can roll with them and invest the money elsewhere.
helmet is very optional. most people who don't wear them complain they are hot and they contribute to goggles/glasses fogging. I find it's not a necessity unless you're wearing night optics.
elbow pads are not needed, you don't really hit anything with your elbows or put much weight on them that they get sore. Knee pads are nice cause kneeling on rocks sucks.. or kneeling in mud/shit/crap on the ground you don't want to wear with you.
Get military glasses, they well exceed safety standards required to play. base z87.1 is single impact 1 Joule, I think 87.1+ is only slightly stronger and again, only single impact. Those types of glasses were meant to be disposable after taking a hit at velocity. An airsoft projectile in canada can reach upwards of 2.3J in a field legal spring rifle. Standard AEGs are 1.5J. Eye wear is not something to be a last minute consideration. Buy the right ones, always inspect the lenses and frames frequently, and be prepared to replace it.
Keep in mind body temperature regulation while you're playing.. wearing a lot of stuff looks cool, but in practical use, may not be much help, and may cause you to achieve heat exhaustion faster or goggles to fog up faster.
I futz with V2s, V3s and V6s. I could be wrong... but probably, most likely not, as far as I know.