If you would like it to be easier to clean then yes, you should.

No it does not. Read this: Does my floor have to be level for tile?

Yes you can. Read this: Floor tiles on a wall

It depends on the tile and the size of the grout lines. Read this: Using the correct type of grout

It depends on where you are installing the tile. Read this: Proper setting materials for tile

Yes, a membrane of some sort is required. Read the article for the different types. Read this: Preparing a shower wall for tile

It depends on the tile size and the look you want. Read this: How large should grout lines be?

Technically? Caulk. Realistically? It depends. Read this: Caulk or grout in corners?

Maybe. Read this article for a more complete answer: Filling grout lines with more grout

You can but it won’t last – so no. Read this: Preparing a shower wall for tile or this: Installing backerboard for floor tile

No there are not. One of the closest things to magic that you can buy is oxygen bleach. It is not bleach! It’s a slight misnomer. This is the main ingredient in products like oxyclean. It works very, very well to clean grout. More information: How to clean grout