Yes, and I'm not sure how to package it yet - it might need to be in a separate package. In AbiWord SVN, it's in the module abiword-plugins. (EDIT: I know it's been done, but I think at the time it was pretty hacky. This is a good enhancement request to file, and a good way for someone to help... I am not so great with debian packaging.)

For fancy things (ToC, math, etc) - aka documents in progress - you should always use the native format of the program. For sharing documents, then you export to an interchange format: RTF, ODT, or PDF. At least that's what I've learned working with this sort of stuff for a while Don't worry, save as a file format will be there. You can hack around this by putting a blank RTF file on your tablet, then when you want a new doc, open it and do a save-as, which will preserve the format.