My phone's notification light will be white when the charge is low and then turns green before 100%. Your 90% sounds about right although I've never really checked it.
If I want to know if it's fully charged I turn on the screen and look at my battery indicator. Both Circle Battery and Battery Indicator Pro (which is what I use, with the 1% hack enabled) will give you a battery read out in your notification bar in 1% increments. So it's not a problem, just the way the notification light works.
As to whether to have the phone on or off, there's no right way. With it off - and no parasitic drain - it will charge faster. But obviously you will miss incoming calls or text. How much faster it would charge would depend on if you were actively using it or it was just sitting there passively. Also charging it via outlet as opposed to the usb on your pc will make a difference. I would recommend plugging it into a wall outlet instead of your computer as I've read that works faster. I usually leave mine on when charging - although I tend to turn it off and on about once a day just to have a fresh boot. Not sure if that helps performance or not, but it seems I don't have glitches others often complain of so I just do it.
Thank you very much! I was wondering if mine was the only one that had the particular problem. On the original Droid, there would be a white light that appeared by the USB charge cable interface and it would turn off ONLY when it was completely charged. This one I've noticed seems to have the light go off when it is fully charged but that requires waiting for the white to turn green THEN off. Actually, the battery charges rather fast given the many negative marks people gave the RAZR for battery life and I've found it to be quite good once you use the task manager and smart actions to reduce unnecessary power drain. Thanks again to both of you!