I might work a deal with the brother for a moving truck and deposit on an apartment to get the heck out.

The 3rd party CPA could accept rent payments and make deposits for a very small fee, which would remove one of the opportunities for any misappropriation.I don't think you have found a smoking gun, but I do think that it would be wise to ask some questions and learn more about what is involved in what your cousin is doing.

He's willing to pay first and last month rent as well as a damage deposit equal to a months rent up front.

Do you pay your mortgage electronically from the account your renter deposits into?

Plus, we get larger sq ft and small fenced back yard for our dog (probably why our rent was so high -- we had to pay pet deposits and pet rent).

Should I remind tenants of their security deposit before they move out (either voluntary or eviction) so they leave place in good shape?

(They will get $5,000 deposit if we fail to close in 3 days.)

Do your due diligence, cost it out, determine the cash received, estimate expenses, have reserves, determine the benefits of holding, buy it and move on. 6 months later review it, then at tax time, thereafter count your money from your deposits to your accounts.

.* Also security deposits cannot mix with your every day bank account, so you'll need an account you can put the security deposit in where it can sit as long as required until the renters move on. 

Direct deposit each month is wonderful.