I've got a full service manual for the 500,520 and 550 Mules.
this is what i have, its in CD format,
Amazon.com: Kawasaki Mule 500 550 Service Repair Maintenance Shop Manual 1991-2004 [CD-ROM]
Paper Manuals:
mule 500 service manual | eBay
they're worth every penny!
I've been down a similar road with the wheel cylinders, there is no rebuild kit for them, only OEM ones for about $90 or there are some on ebay for about $30.
The brakes on these things are regular drum brakes all the way around, just like a car, back when i needed new ones for mine, i checked every auto parts store around here and no cylinders would fit. Also check to be sure it isn't the E-brake locking up and not the hydraulic brakes. the cables can corrode inside and will not release properly when you push the handle down, i had to wiggle and pull on them for them to release.
as far as the battery, check the battery voltage with the meter it idle it should be around 13 volts, and rise with the engine RPM's. if it doesn't. probably your voltage regulator is bad. the manual gives a test for the regulator too.
if you want me to i will be more than happy to send you pages from the CD manual, i can screen shot them and PM them to you.
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