If you got $50,000 in credit cards at 0% interest for 12 months.

lets see no money down interest only... well that was a go to product in 04 to 06 it was called pic a payment.you get get neg am or interest only or fully amortized you picked the payment. you could do no doc just needed decent credit.. first and second  etc etc.. those loans no longer exist and for very good reason.

Water heater, furnace etc,...For a $30K loan I will try credit union w/o points or fees. 15 year is too long for a loan of this size. 

Also, I would recommend finding a real estate agent that you trust, and begin talking to lenders (banks, mortgage brokers, credit unions, etc.)

Cozy only charges a fee if they pay with credit card.

Assuming your credit is good, you have the required down payment, you income qualify, etc, for an investment property the rates should be in the low-to-mid 5's for a 30 year fixed for a 1-4 unit residential property. 

HOME Equity Line of Credit, if it is not your home you cannot get a HELOC. 

The down payment and rehab budget would come out of my home equity line of credit and I would get a new mortgage on the rest.My father will do all the rehab and manage the property, physically.

You might be able to find a bank that will go as high as 90%, but you need to have a really stellar credit score and DTI ratio. 

Based on the proforma financials, the 50 unit shows a vacancy and credit loss projection of 10% and the 80 unit shows a vacancy and credit loss projection of 8% - so 90% occupancy on 50 unit and 92% occupancy on 80 unit if I'm reading correctly.