The "best mods" is a subjective question - what do you want your car to do?
There are many threads on this topic. Probably your best bet would be to use the search option.
The first performance mod you'll need to do is free up the airflow, and you'd do this by removing the catalytic converters in the downpipe (CBE is more or less a noise-maker, and doesn't really do much in terms of power). With the removal of the catalytic converters, you'll want to modify the ECU. There are 3 main types: flashing (e.g., Cobb AP, open-source), piggyback (e.g., UTEC), and standalone (e.g., AEM, Hydra). The most popular form of engine management is the Cobb AP, as it's easy to use, and pretty user friendly. This would put you at StageII.
Many people stop there, as you'll need to get into turbo upgrades beyond that (which will require supporting modifications, as well as a profesisonal tune).
If you want to handle better, look into sway bars and springs.
I'm actually considering doing the backup camera on my car as well. I just haven't decided whether or not it's really worth it yet.