But my credit score dropped from low 800's to low 700s.  

just have to stay away from the low class stuff look at Equity build in Chicago dealing in D and C class they tanked and took 130 million with them.  

Either way, you will find that the price would be 10-15k on the very low side for just the plumbing (not the drywall repair) and probably double that or more if you use an expensive plumber. 

I’d like to pay low or no money down to save capital for the next deal & perhaps a few small renovations.

If your not getting showing a $25 reduction probably isn't going to make much of a difference.You may need to reevaluate the rent.Look at the pictures and ad the PM has if you can.

Prices are high and  cap rates are at historically low levels.  

We begun our search for multifamily and even got preapproved for a conventional mortgage loan in the 500s with 20% down, but as we continue to evaluate many of these properties and their cash flow, it seems like a high cost of entry, ownership with a low return/cash flow.

I like and used these guys here in the past get high marks: www.ConstantContact.comwww.top10emailmarketingservices.comAnyways, another low-cost way to do any of that is to look into and google ideas using cPanel and wHM hosting.

Jestin, that seems like a very low NOI even at 400k.

Let's assume capex is low since you did rehab it prior...300k house for 2k rental isn't that great unless you're banking on appreciation, but at 300k it doesn't sound like it's in a market like that.