It depends on a variety of factors. 

. - What driving factors should I take into account when l'm looking for an up n' coming hot markets?

The pics, snippets and videos of influencers living a particular lifestyle are selling people emtpy dreams. 

Assorted things.Realistically, on a triplex that's not fully rehabbed, without assuming tenant damages I'd be factoring in roof, flooring, HVAC at minimum on nothing more than a 10 year cycle (5 is safer).

They don't even have two-factor authentication (e.g., SMS code on login), or at least don't enforce it for me since I chose to signup using Google.

- How do you factor in the costs of rezoning or obtaining permits, if necessary?

An ounce of prevention is worth a pound of cure. ...I've bought properties with bad sewer lines, but I KNEW what I was buying because of the scope, and I factored that in to my numbers and offer...without the scope, I would have no idea what I was buying, and I would've wound up with a significant unanticipated capex.We inspect every other part of a property before buying.

Rather than comparing Lenders/DSCR loans solely based on these factors, I would advise you to focus on below questions and prioritize what you really need in the DSCR loan/Lender? 

There are several factors that could be affecting that, but definitely not an increase.

I don't think the market is a huge factor UNLESS its a SMALL/rural market where filling a vacancy could take longer because of low/inconsistent demand. 2.