What options have come to our mind are:Facebook adsBandit Signs (tried it before not much success)Direct MailBesides these options what other ones can you think of and which option do you recommend primarily?

upon signing of the lease or move-in of the tenant?

Even if you have to pay them, it is invaluable to make sure you understand what you're signing, when deadlines are, what you need to do before closing, etc etc etc.Can you learn it and do it on your own, sure! 

Maybe owner will sign deed back to your dad but make sure you get title insurance and know if any liens are outstanding.

If one tenant requests to move out then have the one staying requalify and sign a new lease.

That is the best way to structure it, you would treat it the same way as if renting to strangers because it is an arm's length transaction.

I believe I have already signed up on their page the other day but just haven't actually joined the group which I plan to do today.

Investors typically only see dollar signs.

Does he jump jobs-- that's a sign he's hard to work with.   

If they are willing to pay back rent at all you are lucky, getting them to sign some sort of promissory note would probably be your best bet, but talk to a lawyer.