Without solid knowledge on this subject, you can easily end up in hot water. 

When an appraiser is adjusting a comp to match the subject property, he or she will use an adjustment based on the difference in square footage.

subject to, higher risk.

The LLC sells the subject property and buys, for example, 3 replacement properties in a 1031 exchange. 

You could tell them to cancel the listing and you will find someone else to list it after a month not 4 months (the market take is subjective too, all dependent on what your house has compared to others, where it is located, the size of it, and so many other factors).

Administrators are not subject to any such scrutiny and are really just middlemen.

Very subjective question based on your investment knowledge, home market, investment strategy and requirements. 

I would assume that if its for a short term loan, it would likely be better terms with the HELOC but I dont know much about the subject honestly. 

You still claim the income as miscellaneous income and deduct property taxes and mortgage interest (subject to SALT and other high mortgage limitations) on your Schedule A, but that's it.2. 

Are you familiar with Creative Financing such as Subject To (SubTo), SubTail, WRAPS, Short Term Lending, and Bridge loans?