For the paint issue, last time I heard a few years ago burning painted wood here carries a $10,000 fine. Our dumpster company will take any of that debris. I imagine disposal rules vary by location. Recycling is good but contaminating is bad, good judgement is required.

You can get lead test kits at many big box stores.

There is an EPA booklet for proper lead handling and yes you do disturb fine dust when disturbing the boards since it has chalked off and settled into cracks over the years. If you gotta work it, work it wet. Carrying it home to, or using it in a structure with young children or those who will carry them is the biggest concern.
www.epa.gov/lead/pubs/renovation.htm

At the Forest Products Labs, Dr Robert Falk has done research on this. His profile and publications page with Email are here;
http://www.fpl.fs.fed.us/staff/staff--falk-robert.html