Even with that, let’s say 12% after taxes is 8% net.

-Your current STR seems seasonal, so even without a mortgage, you may not achieve year-round cash flow.

Tell your story - I think there's even a subsection of the BP forum called horror stories.

Consumer reports even has a report about how they're better than all the $300+ toilets.

She walked away with $1,500 in hand, and we salvaged the deal, netting $8,500 in the process.That deal reinforced two crucial lessons: first, title issues can create unexpected hurdles, even in straightforward transactions.

So, you will need to stand behind the LLC's debt even though the debt will be in the LLC's name and not on your credit report.3.

Given your assumptions, you are not going to be able to get enough of a loan to fully cover the rehab, even with a hard money loan, so you'll need to pull in cash from elsewhere.One possibility is to have your mom sell you the house with a personal loan, not one attached to the property. 

The new property has to make $50k plus $12k/yr more than the existing property just to break even.

NEVER borrow from a 401K, you are taking pre-taxed dollars and paying it back with after tax dollars, you do not get to return the loan with pre taxed dollars, in addition, some 401K plans do charge interest and maybe even fees, and lastly if you get laid off for some reason, it is a distribution with all the "fun consequences: tax at the last dollar rate, and if you are under 59.5 there is also the additional 10% penalty.Personally I like the HELOC, however you can also sell stocks and do tax harvesting there to offset gains if that is an option

I think your questions are a bit to general and you are going to get even more general responses.