You have to use Visual Basic to be able to write to a textfile. Ask in the
excel programming newsgroup.
You have to use a program that can upload to a server. Either as an addin
or via the Shell command of Visual Basic.
Depends. The OP's question is light on specifics. If he only wants to save a
worksheet as a text file on a file server, it can be done using the menu command
File > Save As. In all versions through 2002/XP, this has been possible without
needing anything to do with XML. It'd be pretty ridiculous if Excel 2003 needed
XML to save worksheets as plain text files.