As a fellow DIY (although of a very wide range...) I find these are my favorite and oft used.
At the very least, get one of the bit holders. You drill *should* have come with this:
http://www.festoolusa.com/products/cordless-drills/centrotec-drill-bits/pilot-bit-with-depth-stop/centrotec-bit-holder-bh-60mm-492539.html
When using a driver bit, this is the one I use 99.5% of the time. I have the locking one, but it's not a necessity.
For drill bits, my suggestion is actually the stubby bit set which just became available in the US.
AND they'll fit in the Systainer with the CXS, which is a must for accessibility.
http://www.festoolusa.com/products/cordless-drills/centrotec-drill-bits/sets/stubby-brad-point-bit-set-38mm-495130.html
I use the 3mm bit (that Jesse linked) all the time, esp. for starting pilot holes for hanging things or for screwing to studs. It's never the "right" size for anything, but it's a great size for nearly anything that isn't precision woodworking, so to speak. Get the replaceable bit type-- plaster, drywall, nails, etc are murder on sharp bits.
The socket drivers are super handy, don't forget those. Coupled with a compact socket set you've got potent flexibility.
Now, if you boost for the Installer's kit, you get everything above, plus almost everything you'd ever need... certainly for a good, long time. Costs a bundle, but worth it's weight in silver.
The right angle chuck is indeed a lifesaver when you need it. If you don't have the stock jacob's chuck, I would recommend you get the 1/2" chuck instead of the stock CXS chuck.
...By the by for anyone... HD has a really good deal going on right now. For $9.99 they're selling a "HDX' brand whole kit of the driver bits, including hex, Torx, Robertson (square), phillips, slotted, etc etc. Like 80 of them. A steal for $10, IMO. Also the compact socket set for $10. Looks to fit nicely in a Mini Sys.