Stock 1g exhaust manifolds are prone to cracking. The 2g exhaust manifold was a better design and less prone to crack. If your a big spender, you can't beat a Forced Performance race manifold. FYI, every year FP has a sale and sells their manifolds for $175 vs. the $275 they sell for the rest of the year.
Plan your dive, and dive your plan. That means you need to decide what you want your car to do and how your going to do it. Just throwing parts at a car is a horrible build plan. it will lead to many many adds in the FS: section.
First things you should do is ALL the preventive maintenance that is suggested in the forums. No point in buying a billion dollar turbo just to have a hundred dollar timing belt break and trash a cylinder head.
Since you mention knowing nothing about turbo cars, I would suggest you start reading untill the sentences become jumbled words, then read some more. Forced induction is an awesome thing, as long as you know how to harness it safely. Since your just learning I would perform all the supporting mods you want first then move onto bigger and better turbos. That means exhaust, turbo inlet, intercooler, and fuel supporting mods. Some stuff will have to go on together, such as turbo and injectors. Other things you can do as you have time/money, fuel pump, fuel pressure regulator, intercooler, exhaust.
Reasearch your planned parts. Not to sound like a follow the crowd kinda guy, but stick to whats proven and be VERY weary about what you buy off of ebay. Some stuff is okay, most is not. and sometimes, nothing beats good old OEM. Those engineers put a lot of time and money into developing a reliable car/parts.
Thats the end of my rant. Build on