The other way is to sell it as a TIC which stands for Tenancy in Common.

Not just academically, but because the public schools were so brain dead when it comes to common sense and they were deeply into "social justice".

(A)In this section:(1)ADULT means a person 18 years of age or older.(2)DOMESTIC PARTNERSHIP means adults living in the same household and sharing common resources of life in a close, personal, and intimate relationship.(3)UNRELATED means not connected by consanguinity, marriage, domestic partnership or adoption.

These are just some of the most common capex items. 

A common arrangement would be for all equity contributed (his 20% and your $50k) to the project receives an annual preferred return based on capital contributed, typically in the 6-9% range, followed by a split of remaining cash flow between the limited partner and the general partner.

Since he is renting a unit, this is a common way for investors to contact homeowners seeing if they are looking to sell a property.

Is that common practice in your experience?

Large common areas would make it a very appealing rental for 4 people, and location 3 blocks to Macalester College and still close enough to two neighboring universities that the demand will always be there for rental.

Or are there other expenses the owner would have to pay (utilities, dumpster, common area maintenance, etc....)

I fix some of their problems and I have been fixing issues in the common areas.