I'd like to build a website for these purposes:- Establish credibility to potential sellers from directed marketing - Blog, track, and show progress and successes from current and past projects completed- Online lead generation As i'm just starting out, only establishing credibility is important to me.

The Housing Authority has nothing to do with what you claim as legitimate expenses.

In addition to helping with the purchase we also provide management services communicating on your behalf with the property manager, building manager, tax authorities, insurance companies and collect payments, pay bills, etc. 

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.