I believe the title would read tenants in common just trying to determine what percentages we might use 60/40, 70/30 etc 

I would also start educating yourself on hard money (youtube university) so you start to understand the terminology, common terms, advantages & disadvantages, difference between local HML and Nationwide HML.

Very common and very fair.But what does it mean? 

Where I live in Los Angeles it is very common for a tenant to offer up-front money because the rental market is extremely competitive and good inventory is scarce. 

Ordinary expenses are those that are common and generally accepted in the business.

There's a good chance the property manager knows the area, knows the rental rates, understands the tenant qualifications common to the area, etc. 

In our subdivision, it is listed as a separate lot with a driveway/common area easement.

Head on over to YouTube and search Turnkey Rental Scam or Turnkey Rental Due Diligence.

For example, Ft Worth has some odd soil settling in some parts of the city that is really common, and we had to mud-jack a house foundation. 

These are not all that common of features in the area (ADU's somewhat more so), and its hard to tell from the identifiable comps how the market might value them.Ultimately this is very usable space - but given an ultimate buyers appraisal may affect their ability to pay, we're trying to think through how an appraisal is likely to value these parts of the property.