Problem with Canvas.Draw

Ok, so I have a lot of problems.

First of all, I am making a crappy little game, but I'm having the following problems:

1. Using Canvas.Draw I can not put use .gifs, what do I have to add on 'uses' to make it work?

2. Once I've put an image with Canvas.Draw how can I remove it?

3. How can make it accept transparent images?

4. How can the buttons get the style of win XP?

Thanks a lot!