Had I not known, common sense would have told me that 11% a month is impossible and makes no sense.

Quote from @Tricia O'Brien: This is a common problem.

This may be true for (1) home with values so low that 6% commissions aren’t worth pursuing, (2) homes in areas most brokers don’t want to service (though I have owned properties in VERY rough areas and never had a problem finding interested brokers or (3) properties needing so much work to make livable that broker marketing would not be effective (much less common today with many brokers specializing in investment properties and many others representing investors as a part of their client base). 

Could/Should the 2 LLC's be tenants in common for the new property purchase?

If the cleaners use the proper chemicals and the mold returns (and there are no leaks, drips, and adequate ventilation), call the mold ghostbusters!

I've never done a partnership, but these are common issues that I don't often see addressed in contracts found online. 

Software is a common question on BiggerPockets.

You might see soft spots on the floors—they’re one of the most common mobile home faults.

Even if one partner takes a more active role, both should understand the motivations and risks associated with investing.It's common for couples to struggle if they're not aligned on investment goals.

For your first question about doing a "subject to" on a hard money loan, it’s possible, but it’s not as common since hard money lenders typically have stricter terms and might not allow a loan to be assumed like a traditional mortgage.