Amenities, location, style, condition, lot size, neighboring homes, etc all play a role in the ARV.I tend to disagree with some of the comments above as I do not believe them all to be accurate, however, the important thing here is to learn how to properly evaluate a property's current and after repair value and there are many factors involved in this process, not just bed/bath and square footage.

I was wondering how to evaluate a purchase price for the sale of the land and building plans for.

Assistance animals do not need to be trained.Info from HUD: "Housing providers are to evaluate a request for a reasonable accommodation to possess an assistance animal in a dwelling using the general principles applicable to all reasonable accommodation requests.

We plan on acquiring smaller multi unit properties initially and as we progress rolling them into larger multi family properties. 

They flip houses themselves, and they are pretty bulldog-ish in evaluating a property as a flip or buy-&-hold.

Stay with  your plan for another year or so and evaluate whether  you should sell tax free or give up the tax free status.  

If not, re-evaluate.

The logical (or maybe traditional) progression is to move onto larger and larger properties, which I've had my eyes open for.

The problem is finding the Path of Progress where your property value is really going up.

A very simple way to start might be one of those websites that give you cost per daft estimates for different repairs.It sounds like you are in the learning phase, so do lots of reading and maybe see if you can find some properties to evaluate for practice.