There's an object in "Objects" directory, called "Fire". If you want it to burn, add a simple line into init field "this inflame true;"
Speaking of intro ending: for example, you have a .sqs script file with all camera angles recorded, etc. At the end of it, when you think everything what you had expected is done, simply create a true/false parameter, like "introend = true". Then, being in editor, generate a trigger, write "introend" in it's condition field and select "End #1". This should be ok.
Questions you ask are very elementary. Search before posting a thread. You might have found what you've been looking for easily.