Looking for some advice on upgrading the cams ?

Plan to turbo in near future but in mean time im gonna stick in some extreme cams (dont worry, im selling them before I turbo) and want to have some advice. Im also running an uprated TB, Induction Kit, Manifold and exhaust. not looking for anything expensive!

please can any one guide me on the following...

1. What to look for ? i.e. do i want a valve springs etc
2. good places to buy
3. Which ones to buy
4. any 2nd hand ones out and abou
5. Cam gears ?

Cheers in advanced