yeah, I think I might have to top mount the trucks
those china batteries have the plugs on top, would that be an issue? they had CNHL Racing Series 6200MAH 7.4V 2S 100C Lipo Battery Hard Case with Deans Plug for RC Evader BX Car RC Truck RC Truggy RC Heli Airplane Drone FPV Racing, or maybe just wait for the 5s’s to restock
do they need an anti spark switch
Yeah the top plugs will probably end up being more hassle.
The battery you linked to is a 2s2p. Don’t get that. It means you are not monitoring every cell individually. Not a good idea.
Yes you need a anti spark switch or loop key if you want to save money.
I might just wait for CNHL 8000mAh 18.5V 5S 30C Lipo Battery to restock. all the 2s from china hobby that aren’t too small are 2s2p and plugs on top
Shoot them an email. Maybe they can tell you when the stock comes in.
what’s the difference between running 2x 5000mah 5s 40c and 5x 5000mah 2s 40c.
Nothing 
the 2s will need more diy wiring and will be thinner.
ive done some measuring and the 5s will fit, i think ill go with CNHL 5000mAh 18.5V 5S 30C LiPo Batteries for all hobbies ?, with a flipsky 4.20