Most PMC's will add extra fees to help the company make some extra revenue.

But you'll have to either manage it yourself and develop a really good skill set in that or get a smaller company that doesn't have too many properties to manage who has a high skill set management for you, but then you need to pay for that.

I financed this property using down payment funds from 403B and a local commercial bank. 15% down from personal funds. 85% down from community commercial bank. 3yr balloon, 20yr amortization, 7% interest rate.

Since the previous owner is getting most of the proceeds does the closing attorney issue him a 1099S and then issue my company one for a much lower amount?

Total waste of time company.

In my case, I have residential rentals in one LLC, commercial properties in another, self-storage in a third, and my real estate company operates in a fourth.

I work for a building materials company now and took their online game from Zero to very engaged in the past few years and it's been really fun.

You could use the sale of your primary and the sale of your investment property to fund the purchase of the land and the beginning of construction. 

Could you recommend a trustworthy and cost-effective company for this? 

These specialized companies, easily found online or here, will create your company’s SD 401(k) plan.