Check tower for HPI gaskets for the manifold. They are the cheap, work well, and you get like 3-5 in a pack... As for the hardware, this is a common problem. Take one of those metric cap-screws to a hardware store and buy 6-8 (it's 2 or 3mm I can't remember which)(need spares) slightly longer units, the one that aren't fully threaded (shouldered) are fine. Now they can be threaded through the header and nuts put on the outside. Those headers are so soft that the threads usually don't last long. Use lock-tite on the nuts too.