On my 2000 3.8l Impala,
I pinpointed the exhaust leak to be coming from around the rear middle sparkplug area by using the smoke from seafoam. Pulled the plug and no carbon was in the threads so it's not the plug leaking. So I have to assumeit is the manifold pr manifold gasket which I am going to find out in the morning after removing the heat shields and pinpointing down using my finger.

So assuming it is the exhaust manifold gasket, has anyone does this themselves? What is the difficulty level and what would a decent shop cost to do this? Those bolts look tough to get at besides being very rust frozen.

-I have not looked into the coolant leak further, but will be after this issue is resolved.
Thanks again!

I would starting soaking the nuts with P-B blaster every night for a week before I started. As I use an air ratchet my time would be different than yours. Depending on corrision I might loosen them by hand. If to tight I have heated them up before breaking them. It isn't a problem unless you break a couple and they don't want to come out. I also have stud removers in a worse case you have to drill them out. Even using an angle drill you might have to pull the head. If you don't have the tools a machine shop will do it for you.
Even in the worst case it still would be cheaper as a mechanic can still break a stud. Gaskets and machine shop labor is cheaper than paying a mechanic.
The cost difference between taking to a dealer and doing it yourself could easily equal a weeks pay.

Phew! Fortunately it is just a pinhole or slight crack along the manufacturing seam on the exhaust manifold. It is too close to try to wrap anything around it though. Does anyone have and product reccomendation? I want this to last especially after I put the heatshields back on. I have some muffler weld cement but I have used it before and it gets brittle; I would like something more permanent. Thanks guys, glad its NOT the gasket!

I never found anything that works even brazing. I think you will need a good used manifold and a new gasket.