For the most part vs focusing on a specific neighborhood or two I would say keep you options open to all. 

That isn't written somewhere specifically that way, but your lender will ask why you would move your primary from (for example) a 2,000 SF SFR to a 750 SF unit in a four plex? 

Specifically, I’m curious about the following:2/2 vs. 3/2 properties: Are there significant advantages to offering a 2/2?

There isnt any one magic "cheapest" loan - it will be highly specific to the deal.

Specifically, Texas has some of the highest insurance and property taxes in the nation, but the appreciation makes up for those high costs in the long run.

I'm wondering how much specifics I need to include for each line item. 

kudos for your specific and thoughtful post. 

If you are going to be doing the rehab work in exchange for equity then that value needs to be determined up front with a specific timeline that you have to adhere to in order to earn your equity.

The best way to do this is to renovate a unit or two to the specifications to bring it up to market.  

I don't have a lot of confidence that those numbers are true (10 DOSC for him, a few dozen for his students), considering the source.