I have a million classified posts showing the style we build. you'll never get the numbers at that rate. your numbers are way off and way too low. work with an experienced general contractor who knows this stuff. 

Those two together create equity.Here's what I want you to understand about “buy and hold” residential real estate:Let’s use a single family home with a property value of $300,000Let’s use an initial loan amount of $240,000Let’s use an interest rate of 7.25%And I’m going to give you $150 of cash flow per monthUse a 5% appreciation amount for your property per yearLet’s see what happens after 5 years:After 5 years…$150 of cash flow per month = $9,000Your mortgage has been paid down to $227,000 = $13,000Your property is now worth $382,000 = $82,000So that’s $9,000 of cash flow, $13,000 of principle buy down, and $82,000 of appreciation.

BTW this will also help you understand local rent rates.

Even under this scenario, with a 50/50 split, you will not be getting paid for doing all the work.Another option would be for you to put in 50% of the purchase price using an LLC that you own 100%, borrow the remaining 50% from your investor as a 2nd position loan at a fair interest rate with points, and borrow the rehab under your personal guarantee.Better, if you can find a lender who will lend to a newbie, and they are out there, you could borrow the purchase money using some of your cash as a down payment, as well as all the rehab funds using a construction loan.

She pays modest pet fee per month.

Would a bank(say like BankofAmer) allow me to assume the low interest rate of another property and blend the interest rate with my current rental property?

Well, it's boring if you don't like scuba, snorkeling, boating, swimming, fishing, the Mayan ruins, Xcaret, riding around in golf carts, a marina, Dolphin Encounter, etc. in a very secure, safe environment that has a very low crime rate, and is constantly patrolled.

If the seller will entertain it you write it into your offer - what you're willing to pay total, loan term, interest rate, down payment. 

Im looking to do a STR in Ocean City Maryland and the vacancy rate, if I'm fully booked in the peak season (May -Sept), would be  58%!.

How I have it set up currently is the owners (my clients) are receiving Airbnb payouts and I send an invoice at the end of the month for my Mgmt fee.