As I've been hunting for the right duplex-fourplex, I've gotten as far as applying for a deal I'd found, only to find out my credit wasn't sufficient.My goal: purchase a small multi-family unit needing a light-medium amount of rehab, but I don't want to come out of pocket very much.First Question:  What options do I have?

Yes, you will have to put 20-30% down (you can get creative and ask the seller you carry this portion if you don’t have it, ask friends and family, partner with someone, etc.) and your credit and DTI must meet the bank requirements. 

Will taking out more credit cards and paying them all on time help? 

. $205k building, and with a 3.5% fha loan, owner occupied, and in a low to moderate income area, with lender credits, I only put down $4,500 with less than $1,800 in upfront costs, inspection, appraisal.

- damages - to roof from Antenna, Ruined lawn by pet urine and bug patched walls that need to be repainted.2 questions - did anyone had experience of small claims court in Washington, by law do I need to refund everything if I am late beyond 21 days. ( everything was deducted from receipts)Does the judgment against me go on Credit history?

Plus you can get an unsecured line of credit or a credit card with a cash advance or even a secured line of credit on your existing rental property. 

Whoever pull your credit ask them what you can do to get higher credit score.

If you need a recommendation for a local bank on the refi --- I'd suggest Credit Union of New Jersey. 

I would recommend refinancing the first 4 with a portfolio loan to get it off your credit report and then you wouldn't have that issue anymore. 

Suppose the worst case scenario transpires, can you borrow from a 401k or credit card at a reasonable interest rate, sell some stock, etc.?