Module stylesheet

[Oprichnik]

Hi guys,

I'm new in cmsms, now i'm reading a tutorial to create my first module.
It seems not very difficult but i have some questions :

- If i made a css file that i want to be by default with the module, how can i set it ?
I looked at guestbook code and i saw that it add an css in the database without any interface (directly with sql code).
It seems not very clean..

- If i want to use ajax in my modules, is it a standard way to do it ?

- How to add a new content type (just a function i think, with a tempate for the form it think)

Thanks