Should I price each individual piece as a stand-alone investment and then combine them for a final offer price or are there either hidden challenges or advantages to a sale like this that would either make it harder or easier to manage?

In fact, I've heard numerous house hack stories of individuals doing exactly what you have mentioned.

What if one individual leaves and a new individual joins in their place (I've never had that happen)?

Joint venturing and partnering with successful individuals can be a powerful strategy.

When an individual property is distressed and hits the market, it's not going to have those instant 12 offers and bid wars flaring up over them that you will see with those purdy perfect white picket fence Hollywood dream homes in areas with optimal school districts for their kids, etc. 

This break-down all of the structure/land requirements you need for each individual zoning.

I'll re-post and ask the questions in individual posts.

Since they can't do each property individually, they use comparables to make broad generalizations to determine percent changes.

We can go dutch and zoom over a cup of java.Careful though...I'll likely give you the same advice as @Eric James Analysis paralysis and shiny object syndrome can easily kill a business before it ever starts. 

working as a server in a restaurant has never been about being a career choice. it is just a stepping stone. however, some waiters make plenty of money because of tips. an individual is the person who decides on their destiny. you chose if you will be a dishwasher for the rest of your life or if you will move onto to something else. we cannot save everyone because they make bad choices. choices have consequences.