I think the thread posted by likefre explains it well and it has generally worked well for me. I think the one thing that Mark really stresses is that just because you have all the bars lite up doesn't mean the battery is 100% charged. In fact, if you look in the status under options you will see the actually percentage; which I believe can be as low as 80% and still show all the bars.
In regards to the first question, I think overnight charging on the first charge is just fine. That is what I did with mine. I got home around 7pm, connected it to the USB during setup and downloaded a few porgrams and then plug it into the wall overnight. Mine is on it's 3rd charge (last charged Sunday and currently at 55%), and I generally get about 3-4 days and I have had it since 11/30, who knows maybe I will make it all week