Photoshop :: Tough Portrait Effect For The Vets

I called the local fire department and made an appointment to do a portrait of a Polish fire fighter in full regalia. I have the image. this is a two part question.

the first one on a technical note. My plan is to super impose him onto a blazing inferno, I am confident I can match the lighting well. The image is super high resolution and I have a lot of hopes pinnedon it to knock some socks off. The problem is (in terms of a super high quality Image, really want to stress that) the image is too clean. I want to smear soot and grease onto the image. is there any way to do that in a completely visible way.

second question. Where can i find the inferno image. I cant find a royalty free image anywhere that is impressive enough. By the way it should be from a distnance as the tongues of flame in a close up shot look unbelievable.