They claim that merely scorching the equipment with a torch won't kill the diseases... They suggest boiling in lye water.... I have taken the Beemaster course taught here in TN by the State of TN bee inspectors... also, the course designed to inspect and move your own hives. What I would suggest, if you're starting out with a new swarm, I would go with new equipment. Bees aren't cheap... neither is equipment.. but at least you'll play it safe and start out with knowns... On used equipment that you have no history on, I wouldn't take a chance. Is there any local bee clubs in your area? If you can find someone to work with and learn beekeeping or possibly a local to buy a few hives from (3 is a good number). As far as opening the hive up, I prefer a sunny day in the 70's... A good rule of thumb is to make sure they're flying good, and you'll probably be ok... When I'm in my hives, I work reasonably fast, the longer you take dabbling around, the quicker the smoke wears off (I only use smoke on the cranky hives when no honey flow is going)
Good luck!
Steve