craftgrrl | What easily hand held sander would be good for taking a bite out the finish but not the wood ?

I'd like to get into taking plain Jane premade things, and making them special, but most the time the items have been sealed, like the wood coasters you buy 7 for 5 dollars.

I need something that would take away a lot of the finish, but not gouge out any of the wood. Also the sander needs to be powerful but hand held. Something like this but maybe smaller.

http://www.ridgid.com/ContentPages/Zap/R2600.asp

Also I bought some paintbrushes from OSh, and Some of them are doing so poorly after one use. The bristles splay out all over the place, and they're dropping little bits of eyelash sized bristles into my paint, and they're also leaving what can only be described as pimple like dots in my paint job. Why is that? They're not totaly absolutely high quality brushes but they're pretty decent, but the first time I used one it didn't do that.