Most lenders require 12 months seasoning but after that they don't care if you move, refinance, or sell. 

The 70% equates to your required return and in most cases you shouldn't buy properties with less than 20-30% margin.Please feel free to reach out and I can help you navigate the process.

Way less hustle, potentially no property management fees required if you self-manage, etc.

Just seemed like a stupid requirement to me but I am having a little trouble with finding a good furnace guy.   

They are adjustable rate.Typically need to be in second lien position (there are exceptions).They are like a credit card (pay it off and use it again as many times as you like during the draw period).There may be a required initial draw amount you may not be allowed to payoff for a certain period of time.Blended rate with a first mortgage and a HELOC in second may be higher rate than just cash-out refinancing.

As I understand it, it's the loan amount that requires the down payment not the potential market value of the property.  

Instead of manually having to turn on Boost, all Premier Host partners will automatically receive higher search rank.As a Premier Host, no action is required to gain this new benefit.

Given these circumstances, I'm thinking SFH LTRs due to lower time and effort input required from me (ideally). 

This is not something that I require, but it was an option I gave them and since they are all in their mid 20's it was their preferred method of payment.

If you're looking at maximum price, that would be the way to go.It might not be so easy to convert it to condo's, given all of requirements.