I want to automate the showing process, by having prospects registering (sending maybe a copy of the DL) and providing them a unique code within a specific time window to go and see the property. 

Here is what I would do.1) Ask to purchase the home owner finance from the owner as is.  2) If he says no, report the home to code enforcement and get it condemned.3) Once condemened, go back to #1.

He even measured the railing on the balcony and discovered it was not up to code.

Denial  there was 60k of code violations as well I could have got those negotiated down to 10k or so.. but the seller would not cooperate so that money came out of her proceeds as well.. 

Ensure it is up to code.

I tried looking on Redfin for comps but I wasn't seeing any multis in that zip code.

The garage was converted and added to the living room/dining room area with a separate laundry room and all done to code. 

I live in grand junction Colorado with the first 3 digits of my zip code that begin with 815.

And then there's building code compliance - how hard is it to do, especially for a foreign-based design?

Currently studying my States Building Codes in preparation for the Contractor exam.