Regarding the Charger...
I use this model from Northern Tool -
http://www.northerntool.com/shop/tools/product_200332201_200332201Been using 3 of them for the past 5 or 6 years, and all I can say is WOW

Has the ability to charge and maintain up to 4 batteries per unit (you need to make/buy an additional harness), and will actually bring an 'iffy' battery back to life.
I use one unit to keep 3 ATV batteries up to snuff (batteries can be left in the ATV, and a quick disconnect is used when hooking the unit up). I just made the harness long enough to reach the battery on each machine, when parked in my shed. Another unit keeps my Valk battery, and my boat start and trolling motor batteries fresh over the winter. Yet a third unit keeps the battery on my '91 Civic ready for summer.
Currently, about $50 each, but I've found them on sale for closer to $30, from time to time.
Black Dog