Welcome to APUG, and the world of Rollei. There's nothing like them, plus digital can never dream of matching what you can capture with one. I don't know of any rebuildable battery, but even if you change it out every couple of years, they are a cheap investment in getting beautiful images. I change the ones in my Contax G system every year.
Now that you've got the 80mm, you really will only need the 50mm wide angle, and you're all set. I shoot with traditional Rollei TLRs, and nowadays mostly with the 3.5E Planar.
Seeing your shots makes me once again think of making the plunge to a 600x system later this year. Congratulations on a camera that will last you a lifetime, and for sharing your photos with us.
Rolleijoe