Using the bone from a spiral cut ham I'm making pork stock for the first time from raw pork bones I bought at the store, and I just opened a spiral cut ham to cut it up. Can I put the cooked ham bone in with the cooking pork bones, since it's all pork anyway? 

Also, in some cultures they consume whatever is soft on meat bones such as the marrow. Is this safe to do with the ham bone, or is it not cooked enough?
If it's a "ham" it's already fully cooked, so there is no danger in eating any part of it. If it's a leg of pork, that's a wholly different animal: different texture, flavor, everything, and...not to belabor the point...it's raw.

That being said, you can lump all the bones in the pot together, no problem. You'll get better results though if you cook the raw bones for a while in the oven first: 425 for ~15 minutes, or until they start to brown a bit. Not only will you lose a little fat, but the crispy carcinogens of the maillard reaction will add more body to your stock.