There seem to be a few resources online but it's hard to tell which are reliable.

The other listings online look pretty stylish.Does anyone with experience in Air BnB have any tips about things I should look out for?

From years of experience, not in REI, but in online forums, skype chat rooms etc. 

Just wondering if there's a quick and reliable online vendor, or should I just take my RE broker's advice (I trust her) and use her "guy" (she's never done home equity through him, to me it just sounds like another person who needs to take a cut)? 

It was built in 1983.I believe i may have to use my $10k line of credit or do a hard money lender.I havent been it.

Treat this as a normal business transaction, do not even consider this as being family.As for the interest/principal calculation's there are numerious calculators on line.

Buy a rekey kit from Change-a-Lock or Primeline, available online or at home centers.

What are the preferred methods of online lein searching?

The good news is it’s simple math and online deal analysis and calculations make the math much easier and with a greater degree of accuracy

in the resi space.the resident is usually not very sophisticated and has lived for free for a long time.. they are use to ducking creditors so will kind of tell you what you want to hear..