Nice and useful thread.
I'd say start with the dialogys, there are detailed instructions on dismantiling and replacement, parts directory, etc.
In fact, with time & the right tools, there's nothing on your car that you cannot repair.
It all depends on how much of your time you want to spare.
Some repairs require expensive equipment that you don't need to buy, like, wheel alignement and
diagnostics, and the most useful tool is a two-post lift.
I think however that having a multimeter helps in most cases - by having the proper values for different sensors you can make pretty good diagnostics on some of them, e.g the lambda/oxigen sensor.
However, whatever you do on your car you have to always watch out for your safety - jacking it up, put the spare tyre underneath; touch
and cables only with gloves, and under no condition dismantle if you have found no advise on how to put it back together.