That's typically the way I operate.

I don't know why you're having a difficult time finding a bank to do a refinance for your investments.This is a very common and typical practice so I would suggest calling a few more banks or credit unions.

Typically 550-650.

Couple things;1) 50% expense rule typically includes all expenses including vacancy.

Typically lenders care more about your debt to income ratio. 

Typical seller financed terms usually assume $10K-$20K downpayment and an interest rate at least a few points north of prime (right now, >7%)   It can be 30yr fixed or 5-10yrs with a balloon.These are really rough guidelines but every deal is different depending on your strategy...

Note investors typically do not buy off exchanges and buy from banks and hedge funds.

That’s your number. https://www.grandrapidsmi.gov/Government/Departments/Office-of-the-City-Treasurer/Property-Tax-EstimatorInsurance: call an agent but typically $800-$1200 for SFH depending on price point. 

I would post an add on BP on what your looking for as there are a lot of note investors who sell one-off notes to investors that typically have higher returns than FCI notes especially on the performing side.

Wasps are not typically caused by the tenant.