First off, :welcome:
As for rooting, ROMs, etc, etc... I personally wouldn't advise trying to get in to all that right off the bat. It can get a bit complicated. I'm not saying you wouldn't be able to do it, but just not perhaps right after getting the phone. Give it a little time to get acclimated to the phone and basic Android functioning then see where else you need to go.
As for a clock while charging, if you purchased a home dock for the phone, there should be a large clock on the screen when the phone is charging in this dock by default. If you don't use the dock, there still should be a clock on the screen while charging. Open the app drawer (grey button at bottom of screen) and select settings, then applications, then development, and make sure the box for "stay awake" is checked. Then, once you plug your phone in, press the power button once to sleep the screen and then again to wake it up. It should wake up on your lock screen, which will have the time in somewhat large font, and it will stay on that screen and not go to sleep for as long as you have it plugged in.
