Uninstall system app?

[webaddict]

Hello wonderful people. I'm new to this android technology and to this forum as well.

I have my tablet rooted, and wanting to uninstall some unnecessary system app (like gallery, email, etc)

Questions:
1. Is uninstalling the app as simple as removing the *.apk file from the /system/app folder?
2. How can I tell which apps are safe to remove and which are necessary for the tablet to work?

Thanks!!