If I could get an estimate on the time and cost for the variance, the next step would be to engage an architect or developer.

For example, you can write something like:"Spoke with GC for 1 hour regarding renovations for STR property, discussed scope of work, timeline, and cost estimates." 

the reality is you have negative cash flow when properly estimating the expenses on the 3 rentals (no way 3 rentals have $1300/month maintenance/cap ex, pm, vacancy, and misc total (basically $433 per property).  

Unable to estimate appreciation potential because it’s brand new and no room to add on or make improvements, but over time I do think some appreciation due to prime location.

There is a banner on the top that states "Listing cannot be published without a Zillow Advertising Contract," I filled it out but have gotten no email confirmation or estimated time of completion. 

After we build the structure, is there an general estimate of how much the property/house will appraise for when said and done?

Just to use as a starting point to estimate costs?

In terms of running numbers, I find that using Rentometer's LTR estimate for your location plus 30% is a good number for right now.

Do you know how to estimate rehab costs? 

Using my knowledge, I estimated the remodel cost, Found the estimated Resale value using comps.