New to Androids

Just got my first Android. First tried an HTC Merge for about 3 weeks only because it advertised that it could take an overseas SIM card (most US Cellular phones do not) Went with it even though I really like the LG Genesis. Got my husband the Genesis so we played with both. After 3 weeks and many glitches with the Merge, I changed to the Genesis.

After 2 weeks, I love the Genesis. When you look under the battery where the SD card goes, you can see a place for a SIM card. (It looks like it is anyways!)
So now my questions!

1. Does anyone know if that is what the extra slot is for? A SIM card?

2. Is it possible that I could be on the internet and not know it? Remember I am new to smartphones. If I am on the internet and push the back button, does that take me off the internet? Is there a way I can lock out the internet until I add a password? Is there an app?

3. I need a very protective case for my husband. He drops cell phones. I also need a screen protector. Has anyone compared the anti-glare with the clear protectors using the Genesis?

4. Am I right in assuming that when I use a wallpaper that has animation, it is using more battery than one without animation?
Thanks for any help,
pypeke