I'm new to Kindle and new to tablets and looking for a few answers to probably "stupid" questions:

1. When you leave an app, the browser, whatever, is there no need (or way) to close it as on a desktop or laptop?
2. My Kindle HD seems to take a long time (but probably less than 20-30 seconds) to load the PIN screen. Is this normal?
3. Often when I check runnning apps, there are tons of them and I usually force close the games, etc. thinking they are memory hogs. There are also a bunch of Kindle things running. Should I leave these alone?

Thanks for any help. I'm glad this forum is available for users since the manual is pretty basic.