these are normal issues with the charger from the wall to the phone. Once i'm off the charger, my battery shoots down to 80%-ish within an hour or so. This IS because it doesn't continuously charge when its finally full.
I bought the 2 batteries and wall charger(which mounts a battery in it) for $12 bucks from hong kong, and that is truely the way to charge to full. After i pop in one from the HK charger, it will stay at 100% for atleast 20-30 mins.
It is definitely HTC's hardware/software implementation to make sure this doesn't happen
there is no issue. But a spare external battery charger is the way to solve this problem if it is really beatin you up inside.
also, if you rooted your phone, after wiping the battery stats, could potentially show you different behavior then before. I don't wipe my battery stats (just FYI)