fyi, fairly cheap but useable looking diy charger:
$200 Build your own intelligent charger. - DIY Electric Car Forums
Also a lot of folks don't worry about a bms, but they will install something very simple like this so they know it is time to balance the cells manually (i.e. once a week max), it isn't perfect but it is better than nothing and very cheap (even number of cells in pack required, never a problem with leaf modules):
And pack voltage/current of course. And the consensus (in the absence of active balancing) seems to be to bottom balance when you do need to.
The contactor allows key control of the pack, the controller might suck a lot of juice when idle. Sometimes it a safety thing I guess, the controller can open the contactor in some situations, don't know what those are off the top of my head, but if it doesn't then a manual switch will do too(thinking it should be at ground level but not sure, certainly it should be of the big red easy to press button variety).