Hi wok

Firstly don't be too apologetic about your english ... we are all from different cultures and its not a given that everyone will be good in English - as long as you are understandable.

About the sound card - I don't know if it will work.

About controlling the N800 remotely - or controlling your computer remotely from the N800 - both ways are possible with VNC software.

VNC consists of a server and a client.
Install the server on the computer, if you want to control the desktop remote;ly from the N800 - with the VNC client installed on the N800, or the other way if you want to control the N800 remotely from the desktop.

About processing, maybe it is too graphic intensive for it to work on the N800 (it doesn't have a seperate GPU etc). As of now I haven't heard of processing ported to the Maemo platform as yet.