As you mentioned only half of the cash out is used to construct the new addition,  only interest related to the debt that was actually used, half in this case,  to fund the new remodel is tax deductible. 

I would expect a PM to cost 11%, putting you at about 44% not including debt service or cap ex.

Nope):1 - Learn how to analyze with real numbers2 - Learn what a plan is, and how to develop one for REI3 - Learn what is important to a REI...and then start thinking like one, instead of a homeowner.4 - Learn how Money Works5 - Learn how to analyze Markets (not economic...geographic) in order to find where the properties whose profiles match the criteria you need to execute the plan you developed.6 - Learn how to eliminate any emotions, both yours and the ones you think are driving forces for the buyers/renters that will be your clients7 - Learn how to eliminate any for of "rationalization" (most expensive word a REI can use) from your thoughts.8...and last, for now, learn how to describe yourself (when asked what you do for a living) as a "Successful Real Estate Investor". 

We've spent the last 15 months paying off $30k in credit card debt, $90k in student loans, $10k to her parents, and are getting ready to pay off the remaining $25k on an auto loan. 

Hey @Brian Leigh I would personally use a line of credit if you are able to get one, should be cheaper debt

@Chadd Brandon For the most part I use my cash and credit to purchase, rehab and carry it for 6 months before I finance to long term debt and get all of my money back.

I also have $80k in student loan debt that I’m aggressively paying down.

Additionally, some residents will offer to pay for part or all of the ramp and its removal, reducing or eliminating the financial burden on the property owner.Your local laws might be different.

So I’m paying off school debt and saving money for a conventional loan vs or may do a heloc.

You have $400k in new debt that you have zero track record of paying on time, so temporarily you're a higher risk.As you establish a new on time payment history over the next few months, your FICO will bump up higher than that drop, call it 75 points.