I typically figure 7.5% of rent each for repairs & CapEx.

Anything above $200K is typically sitting on the market longer with fewer showings. 

Lending for investment properties typically require 20 to 30 percent.

In just over a year I earned $103k by getting creative with what would typically be a standard flip or wholesale deal.

But it sounds like your properties are not the typical vacation rental property. 

Keep in mind that Habitat typically requires that if the owner intends on selling the home there is typically a duration period (10-20 years).

Multi family can be intimidating but as you grow your business it typically makes more sense as it is easier to finance, and manage than the same amount of units than SFH's. 

They aren't all that great typically.

Water heaters typically have about a 10 year lifespan.Hope this helps.

Also, limited partnerships need to have a general partner who has unlimited liability, so if you're looking for limited liability, you essentially would need to create two entities for an LP (the LP itself and an LLC to act as the GP).