They need to carry basic hazard insurance while the builder carries the liability.  

Another option is to ask your insurance company what the replacement costs would be as they have all that data as well and use it for underwriting policies. 

In all honesty I would guess that 90% of the people he arrests are tenants not home owners. 

like knowing where the most cash (investor) purchases are happening, or where the most sought after areas where retail (homeowners/families) buyers are buying?

Do I need to purchase title insurance? 

Maintenance, Taxes, Insurance will never stay the same.

Maybe owner will sign deed back to your dad but make sure you get title insurance and know if any liens are outstanding.

Should tenants have renters insurance?

I am hoping to get some guidance on my current revenue/expense assumptions:Rent / Purchase Price -> 1.0% to 1.1% (model set-up for varying ranges)Vacancy Rate -> 0 to 10% (model set-up for varying ranges) Property Tax -> ~2.5% (looking at Tarrant County property site for reference)Insurance -> ~0.9% (based on my personal residence)Property Mgmt.

I see a lot of people waste homeowners valuable time for potential resolutions because they are unaware of all the factors relating to the foreclosure and details of the debt associated with property.