Have you ever considered adding the "Try using the search button" to your signature, it seemes every second post of yours uses it?
Hi - welcome to the forums.
Stock 33s - depending upon the driver, track, condition of the car etc should be good for a 13-14 second 1/4 mile
Stock turbos are quite good, and will last a long time. The usual problem is that we all want more power, so as we increase the boost we risk damaging the turbo. Most people feel increasing the boost up to around 12psi (from a factory set 7psi) should be OK, but after that you reduce the life of the turbo.
As for common problems, there arn't really that many. Only ones I can think off are that the "Radius Rod Bushes"?? are often a little worn out when they arrive from Japan and need to be changed (not expensive) and that at 100,000km you need to change the timing belt (and its a good idea to do the water pump aswell) which isny the cheapest service (but not bad compared to other cars).
Common modifications usually include :
better exhaust (3 inch) from the turbo back
Front mount intercooler to replace the small factory one
Increase the boost - Bleed valves are cheap, but Electronic boost controllers do a better job.
After that you would consider aftermarket engine management such as a Power FC or other.
Now the power bug has bit hard, so you want to get a biger turbo, improve the fuel system (new pump and injectors) etc etc
The suspension and handeling of the 33's is quite good, so you dont need to modify it as soon as many other cars, but its worth considering a good set of tyres so you can use the power. Other mods often include a Hicas lock kit, Pineapples (to adjust the rear end geometry) and better quality brake pads to help you stop quicker (no real need to change the rotors unless you go for huge power)
Hope that is of some help.