Hi,
Go to local hardware store for bolts. A good one will have choices regarding size and, I hope, stength. Regarding the hold down clamp for the EGR valve,that's a tougher issue. I suggest you look on the internet, and in absence of results, Fabricate your own holddown from flat stock steel. A torch and a grinder will do the job.If you don't have access to these, a welding shop can help. Good luck!