Well, I got it all apart:
Details in the thread in my signature, but the head needs a full rebuild.
On the exhaust manifold... I strongly suspect that it is not stainless. My manifold will strongly attract a magnet. Most common stainless steels are either not magnetic or weakly magnetic. Because of this, I plan to weld mine with conventional steel MIG wire. My crack is also much smaller, only on the front side of the manifold.