I like it is an alternative investment vehicle, and my goal is to have two or three sources of passive cash flow over time.  

I have been reading and reading to narrow down what investment vehicles to choose.

"Where is" generally refers to movable,,personal property...cars, trucks, boats, etc., and not used for real property.

Generally an s-corp is the absolute worst vehicle for real estate investing.

That is not possible within IRS rules, other than by taking a (potentially taxable) distribution from the IRA.The questions I would suggest you ask are related to keeping the Roth IRA as a tax-sheltered vehicle.  

One should be  devoting his or her time building similar vehicles while competing with the masses in these competitive times.

Even if money weren't a concern, two companies will limit me in other ways such as what marketing would I choose to put on vehicles, introducing two companies to people I network with, etc. 

This would be a commercial note limited to 80% of the trade-in values of the vehicles and would be priced around WSJP + 2.50% with a 1% origination fee of the loan amount.

My plan involved using the 150k to pay off my current loan and the remainder of a vehicle loan which would reduce my monthly bills by 350$ but the 150k loan would have to have a term of 30 years.

If you are running to the hardware store on a very frequent basis, or using your vehicle to haul significant amounts of materials, the IRS could question your level of involvement and whether you are providing services to the IRA.