first off, you don't NEED an external wastegate so long as the turbo you pick up has an integrated one which most do. You can tell because there will be cylinder looking thing mounted to the side of the housing with and arm that goes to the exhaust housing. You will need some sort of fuel management system whether it be an adjustable fuel pressure regulator, etc. Search the Honda tech forum to see what some of them are running. The intercooler just sits between the turbo and throttle body, if you don't run one then you just have the pipe going from the turbo to the throttle body. You must buy a turbo manifold for the turbo flange type you are getting. I ordered my oil lines and shit from vecco.net, can be found on e-bay. Check out the for sale forums too, people are selling there old setups all the time and you can find hella deals as well.

You really need to do some more research. Start by talking with people at local honda meets and what not and see what setups they are running, as well as surf through the honda tech forum.