act...What I like about this property: is that it has seller financing which could get me in the game sooner (without using my personal credit). 

Line of credit, cash out refi?

No you do whats called a credit bid.. you already have your money in the deal and your expenses  and tax's if you paid those.. so what ever your owed plus late fee's and interest and foreclosure costs any money paid to senior lender and insurance any property tax etc.. all that is added into your credit bid that your entitled to.. your not entitled to more though. 

Here’s the catch: The brother would be stretching to make the rent that I’m currently getting on some of the other properties I own in the neighborhood and, apparently, his credit isn’t great.

I looked at the exterior the other day and it most likely is going to need a new roof soon, also the exterior could use a new paint job but nothing too terrible.

If you have no money and he has it all, or you're an 872 credit score and he's a 514 it can still be done...but would you or he want to? 

I recommend looking into the local credit unions first (Charlotte Metro, Truliant, etc.).Also, in addition to the meetings @Karen Rittenhouse mentioned, I'd invite you to come out to the next networking meetup of local BiggerPocket members:Charlotte, NC REI Networking Meetup - Tues.

Lima One is great too especially if you have credit or debt to income issues to personally get a loan

Also HELOC's get more restrictive or lenders get rid of credit lines all together.

We get charged 3%, whether our renter pays from their checking account or whether they use a credit card.