Bah, now my post disappeared - tabbed browsing is dangerous when you are not quite awake.

Anyway, here's a short summary of what I wrote.

The file for startup programs is called .xinitrc and should be found in the users homedir. If not, just create it. Google for the syntax of this file, but basically it is just a list of commands to run at startup of the GUI, one per line. Similarly you will want to take a look at the .xsession file. The browser is firefox 3, so opening a webpage on startup is done by starting it with the url as a parameter - check firefox docs for syntax if any.

As for transfering files, just make sure the tablet is running an ssh server and use SFTP to it. Either use OpenSSHd or DropBear - both available from the Garage.

The startup settings... I'm not quite sure I know what you mean by this. The description is a bit too generic. But my guess is that whatever you want, you can do by editing/uploading the config files to the tablet by SSH/SFTP.

Splash image can be changed. Search this forum to find out how. I'm sure that the description by other people is much better than I can do.