All guns are lipo ready, how long it will last running a lipo is the real question. Personally I prefer a regular 9.6, 20 RPS is enough for me and I don't have to worry about how long my gearbox will last. NiMH batteries don't have battery memory, just get a smart charger so you don't burn them out. I've only had my batteries die in the field a few times, that's why I bring two. On the other hand, when I use my large 9.6 I once fielded it, left it sitting around for a month and then went to a milsim and forgot to charge it, yet the battery still had enough juice.
As long as you keep the gun under 400 fps and don't use a lipo, you can leave pretty much any decent gun stock. King Arms M4 is good. If you want to throw in a bit more money the KWA is much more solid. I'm a fan of CA guns so I'd recommend any one of them, but the stock hop up isn't very good. If you're willing to drop around the 500 mark you could look into VFC.
Also do your best to avoid getting a bolt action as your first gun, you'll regret it. I've pumped enough crap into my M14 that it's more accurate than any bolt action I've seen so there is really no benefit in having a bolt action gun.
Guardians of Asgaard - KF32
VFC H&K 416C
VFC KAC SR16 JL Billet SBR
TM FN Five-seveN