Questions/Concerns about rooting

[zeppelinated]

I really want to root my phone, but I have a couple concerns/questions.

1. Is rooting actually as complicated/hard as it looks?

2. The thing I read somewhere about sandisk memory card not working.. is this accurate?

3. If I mess up, is it hard to fix?

and finally

4. What are ROMS? (I'm a noob, cut me slack)

Any input from experienced Android users would be greatly appreciated!