9s battery and charger for e-bike?

[A RC Dude]

Hey guys, I am building an e-bike with a 36v 30a (1,000W) motor. I've bought everything and got all the mounting planned. Just got to get the battery and low voltage warning figured out.

I found this battery on hobbyking that would be perfect to use (probably put 2 (possibly 3 or 4) of them in parallel) but need some help with a charger or some advice.

-What would be a decent 9s charger without braking the bank? I am perfectly fine with an overnight charger (100w would work great). I alredy use a 360W power supply for the RC's but only have a 6s charger. I did find some 9s chargers but that require an external balancer.
-Should I try to buy 6 3s batteries instead and wire in 9s2p (this will be way more expensive than that $50 battery) or just call it fine with an 8s battery?
-What should I do for a low voltage warning since the speed control doesn't have one? I already have a voltmeter mounted and could resort to manually stopping at a certain voltage but I could always get distracted...lol

My college campus is full of fairly steep hills so I would like to keep as much power as I could. A 36v (18 cell) pb battery should peak at around 37.8v (2.1v/c) witch would be the exact same as a 9s LiPo battery witch is were I got the 9s from.

Any advice/suggestions guys?