These are all common pitfalls I see people when doing flips, BRRRRS or even multifamily.

Any tips on avoiding common mistakes?

If it is a larger house and the renter group is families consider that moving in the school year is less common.

Location, Common rents and things like ARV are also things to consider in advance.

Looks like we share more in common than our names :) I'd be interested in speaking.

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?

MInut has a low average review (mid-3s I think) on Amazon which is a bit of a red flag. 1 per room at a total of $60/month sounds excessive for something that is not likely to be a common occurrence. 

Second, the building code, IRC/IBC, defines a townhouse as zero lot line (zero setback) homes that are on their own separate parcels and share a common wall.

With four plex you have to pay utilities for the hallway and common areas, also maintain and clean the common areas, because the tenants won''t.

So this is common thought and why it is a real challenge to get debt secured by the ADU value add at higher than 50% of the addition cost.