Phone call with email follow up or email so there's a paper trail.

Looking to invest in a few properties over the next 5-10 years and want to get a sense for tenants, common issues, etc.

Yet, it seems common practice for wholesalers to use this contingency to back out of the contract simply because they have not found a buyer within the inspection period.

You would have to create an HOA to manage the common area and keep control of that or create a self-managing HOA for the four owners to manage together.

From the conferences I have attended, all I have read I think 3x rent is more common but that doesn't mean your PM is wrong. 

My questions are: 1) Is this a common concept in commercial properties that the tenant is responsible to repair, maintain, and replace anything in their leased space regardless of the cause?

Your question is a very common question, and I can appreciate your concern here.

Are these common now?

Very common. 

It's not common that loans in good standing are called due, but it does happen, regardless of what people tell you.