No, just get a harness that can hold a bunch of 140 round pods. I suggest a five pack. So lesse...
140+
140+
140+
140+
140.... uhh hmm.. good question.
I've used a surplus vest before along with a rag-tag collection of converted ammo pouches and have to say that the purpose-built paintball packs are far superior: easier to pot up, carry and they don't stick out as much.
One thing I would suggest if you have a remote is getting a yoke harness to shift the weight to your shoulders - much easier on the back when you are throwing yourself around.
You can get a commando vest purpose built for paintball (can be picked up on ebay for about $30) but would really only be useful for long scenario games. If you just play rec ball then a good pot pak is a far better option. Reasons stated above
i don't think you should waste your money on a protection veste with harnesses, i think you should get a harness that can hold a whole bunch of tubes and take the pain of a paintball hitting you.
i wear an assault vest as a harness to hold up my pack, extra ammo antd the pots on my chest means my nipple piercings don't get hurt if i get shot there