For example, S-Corp isn't an entity but a tax status. 

As an example, I'm working with a first time investor who qualifies for 300k single family OR 475k three units.

Warren Buffet and Alex Hermozi are a couple other great examples.

Here are some example figures that you could expect (based on today's 5-year treasury rate) for your refinance.

We are thinking about putting an offer in on a 235k vacation condo in our favorite popular beach town, that would have a typical ROI of about 10% annually.

From there there's typically a sliding scale pre-payment penalty.

For example, if you rent is $4k per month, do you really think you need 50% for expenses or $2k per month, maybe it is a beatup property, but you are probably not getting $4k per month on a junk property. 

I typically have a new tenant under contract before the old tenant vacates. 

Those are typically meant for larger projects and with well versed Contractors.

To give an idea of the market here are some examples of recently sold and active coastal vacation rentals and their current and projected production: - Oceanview 4/3 SFR.