Personally, I have always backed up, cleaned and then restored on every rom update I've done.
That said - Lollipop is supposed to change the game for us because apps will precompile rather than run in the Dalvik virtual machine. If the Dalvik cache goes away, then no longer as big a deal because the other caches you can clear without a reset.
That's the theory.
Did you get the Sense or GPE edition? I think only the GPE is getting Lollipop right away (or so).
And the battery charge thing - imo you're done so the short answer is no, you won't have to do this every time.
Once your home on 3G, please start GSam, and ok to home out.
It has a radio vs power graph so if there's something funny with the 3G or your phone's radios, that ought to help expose it.