Lipo batteries ?
 

If a battery says '4s2p'. is that considered 4 cells?

Which battery would you pick for a Revo for street and bashing? Taking everything into consideration, runtime, weight, and price which do you like the best? If you have other suggestions let me know.
All of these are relatively the same dimensions.

...MaxAmps...
20a, 30a, 50a

1. 8000 4s2p 14.8v
725g $275

2. 6000 4s2p 14.8v
590g $200

3. 5000 4s 14.8v
450g $175

...Flightpower EVO...
25a, 35a, 50a

4. 4900 4s 14.8v
433g $235

5. 5000 5s
?g $250

or ...ThunderPower...
25a, 35a, 50a

6. 4600 4s 14.8v
457g $215

7. 5000 4s 14.8v
490g $240

Anyone wanna guess the runtime I would get? Its a neu 1512 2000kv, Quark 125b in a stock revo.

if it says 4s2p there 8 cells in the pack, 4 x series 2x parallel.