They said last year they brought in 5500 per month total.

Probably your cost would be around 750-900 for the first one and 400-500 for the second one totaling 1100-1400 for total transaction. 

Here is my current understanding on 2a - how to calculate the depreciatin of replacement properties.Realized gain for R = capital gain + depreciation = 168K.The total basis for property A & B are (225K+150K) + purchase cost let's say 8K - realized gain for R = 215KThe basis is splite proportionally between A & B - So A is 60% at 129K and B is at 86KWhat I am not clear now is how is the land value deducted from the basis - percentage (of land to purchase price) based or absolute land value based.   

Right now my husband and I have about 12 units total.

In Virginia, it's actually written into the landlord tenant laws that landlord can require a renter's insurance policy and actually purchase one and charge the tenant if tenant chooses not to purchase one, as long as total cost of security deposit and renter's policy equals less than 2 months' rent.  

TOTAL nightmare to find landlord insurance - I spent 2 months of heartache and runaround to eventually find a good rate. 

These are two totally different vehicles. 

If that's the case, in the future you might do as @Amy Beth suggested and make it so all tenants are "jointly and severally liable" for the total rent. 

Would it be feasible for; partner to contribute 20% down payment with SDIRA or SOLO401K and personally borrow 30% (for his total of 50%) and my to borrow the other 50%?

Total working time: five hours.”I'll call this the Kiyosaki Courthouse 2-Step for ease of reference.