I didn't pick it up till I was older and people tended to assume I had been doing it for a long time and it gave me instant credibility (deserved or not).

Also inquire as to whether the person you are negotiating with has authority to speak for the selling group.

If I structure my LLC in DC, will I be authorized to do business in Maryland or Virginia without having to establish an additional LLC or partnership within those states?

BiggerPockets sells a book that walks through the entire methodology for estimating rehab costs (disclosure: I'm the author):http://www.biggerpockets.com/flippingbook

Now to either find a property or an agent. any suggestions on where to look or who to call for credible listings ?

Only some properties are authorized to be "vacation rentals", and my understanding is that no additional vacation rental licenses are being distributed at this time.You could of course do as you please, but I figured you should at least know the risk involved.

Assuming a loan means you actually become the new borrower on the loan, relieving the old borrower of liability, with the authorization of the lender, and after going through an application process.  

This will determine how much rent you can request from the Housing Authority and of course it depends on how much the tenant can afford.

You should really try to get a handle on those two because if you can do those things accurately you'll build credibility and buyers will trust you.Keep in mind that the average direct mail campaign gets a 2-3% response rate and you'll probably lock up 1-2% of those in contract.  

@ed Account ClosedI believe if you work closely with the housing authority and tenant keeping records of anniversary dates, inspection dates and attending landlord quarterly meeting you should be fine.