Should I form a LLC (or other entity) prior to the first investment purchase?

I am only now purchasing my first rental, though my husband already had one prior to our marriage. 

Lastly, when a self-employed individual maintains more than one trade or business, the questionarises as to whether the limit is based on the sum of earned income or loss from all trades orbusinesses under common control [as defined in IRC 414( c)) as modified by IRC 415(h)], or ifonly the trade or business maintaining the plan being tested is used.For purposes of the IRC 415limit, earned income for the self-employed individual is based on the sum of the earned incomefrom all the controlled trades or businesses, regardless of whether the related employer maintainsa qualified plan [Reg. 1.415-2(d)(6)].EXAMPLE: Andy, a sole proprietor, operates a law practice as a sole proprietorand has $100,000 of self-employment income from such practice for 2008 (prior tothe reduction for one-half of self-employment tax).

I keep any excess cash-flow and any time prior to the expiration of the lease in 5 years, I have the option to purchase the properties for whatever principle balance is remaining at that time.

A prior thread on BiggerPockets suggested using a 20% vacancy rate for offices due to their volatility, but I'm having a hard time making that case to the broker based on the market data available.

Might be of interest to some of you if ever in this situation.ERRORS & OMISSIONS CLAIMS STUDIES Claim Study 1: Square Footage Discrepancy Facts: Prior to marketing the subject property, the listing agent drew a floor plan of the house showing 3,500 square feet.

In each of the prior deals, the purchaser was utilizing bank financing, and the lenders refused to finance the transaction because of the existence of the easement and sewer structure."

So that abnormal thing about this is that I bought the property recently after a long forclosure and auction, and I have the names and contacts for most but not all the people, and I have no prior lease information.

I know there were a couple expected to be auction today that got pushed back just prior to their number being called...

My husband agreed to remove an inspection contingency from the contract offer prior to the home inspection.