A few general comments:

The idea is to light the wildfire first, before torching the homes. Or take advantage of the naturally occurring fire to torch a property.

This is a common practice in urban arson, torch a nearby abandoned building just prior to the real target.

Re: Fires started by firefighters.

http://www.state.sc.us/forest/lear.htm

Google ‘firefighter arson’ for *LOTS* of hits.

For the record this is *purely* speculation on my part. I would still like to see the data I mentioned after the smoke clears.