The one thing I forgot to ask, however, is whether or not it matters if I pay these costs from my personal checking vs. the LLC checking account.I am a single member LLC and plan to maintain the "disregarded entity" status for tax purposes. 

Florida courts have held that a single member LLC is a disregarded entity in the case of legal action.

If it is state law then disregard.

They are probably disregarding things like vacancy, maintenance, property management, paying the water bill(its on one meter so the landlord likely pays it), etc.

You can also ask for a copy of Schedule E of the seller's tax returns, with SSNs and other properties blacked out, to see what they tell the IRS the cost of utilities, etc, actually is.Whatever the sellers claim rents, NOI, etc, is, you can go ahead and disregard those numbers.

Disregard any pro forma and instead ask for a current T12 and rent roll.

You can also do the same with a NV company that files a lien on one of the properties because NV companies do not reveal owners or partners.If you have sole member LLCs create a management corporation so your liability is limited because LLCs are disregarded entity for the IRS and in FL they are also disregarded for the Courts.For real estate property, FL protects your homestead for the its value.

However, you will rarely find someone on Bigger Pockets that would disregard your question.

I would keep your 3 properties in the LLC as a disregarded entitity and just report it on your 1040.

I actually came across BiggerPockets during my search for info in the first couple of months, disregarded it then since I wasn't looking to be a REI then.