You need a series 2 TIVO (which practically everyone sold in the last couple of years are), a home network, and the TIVO server software. Plus, you need to request a software update on your TIVO unit (that can be done in the settings menu, I think)
To burn to DVD, you need to download another piece of software on your computer. TIVO's web site describes it all fairly well.
As far as mods, run a GOOGLE on TIVO mods. There are a bunch of things I have never tried. One I did try with the old TIVO was a code that turned your advance button into a 30 second leap forward. The advance button normally jumps you ahead like 15 or 30 minutes. But with the mod, you could skip commercials. Four clicks and you buzzed right through a 2 minute commercial break without having to even watch them on fast forward.
TIVO did not make that feature standard out of fear of reprisals from the networks and Hollywood. And I don't know if it still works with the newer series 2 units.