RE: charging starter battery
For your starter battery, you want around a 7AH lead acid, gell cell battery. THe last is vey important as I've see three cases where a guy as knocked his motorcycle battery over and spilled acid in his car.
Besides uning the battery for the starter, I also have a power panned and it if for pumping fuel and for my glow starter. I have a couple of the battery in the handle sticks, but after using the pannel for the iginter, I never use the sticks any more. Last, I picked up a field charger and my starter battery is the power source for it also.
I used to have one of the old Montrola bricks, and then got a some of the first flip phones. THe wall warts for thouse put up 13.8V at about 1 amp, just right for my charger. I charge the battery overnight about every six weeks. A little more often if I'm doing a lot of battery charging from it. A car battery charger will work well, and like suggested above, a low amp one, 1 or 2 amps is enough.
The Lead Acid batteries will hold a charge for months if not over a year, and I expect used just for starting, you could get close to 4 months off one charge flying three times a week.
Don