In case anyone stumbles upon this post, and has the same question, I just received the answer from the vendor I purchased my eGo PCC from:
"Hello, we do not recommend charging the battery in the pcc while the pcc is charging, that puts a lot of stress on the battery. As far as length of time to charge, the person that uses a pcc in
shop charges their charging case over night. There is no real way to overcharge the case as the circuitry in it will stop taking in power as the battery gets full."