With massive assumptions as well as no verification of numbers it could be ~8% cap-ish. 

According to the Fair Housing Act and the Americans with Disabilities Act:Even if a landlord has a no pet policy in place, the law does not consider service animals as pets and therefore the service animal is exempt from such a restriction.Service animals are allowed anywhere a person would go, including food areas that would normally restrict an animal’s presence.Landlords cannot charge a pet deposit or pet fee for service animals, however the tenant is liable for any damage that the service animal may cause.Landlords can require written verification from the tenant’s health care provider that they are disabled but cannot ask for any specifics about the disability.Landlords can require written verification from the tenant’s health care provider that the service animal is needed.Landlords can request copies of the animal’s health records to prove the animal is in good health, parasite-free and immunized/vaccinated.Landlords can write warnings or even evict a tenant with a service animal if the animal is disturbing others, posing a threat to others or causing considerable damage to the property.In other words, you can ask for appropriate paperwork concerning the tenant’s need for the service animal and to verify the animal’s health. 

I bought 5 homes in 5 years thanks to being in the Army between ages 22-27.

If they are VERY professional, they will have their processes in writing as verification that policies are enforced equally and fairly by their entire staff.6.

I'm interested in buying single family (even though I hate this idea at a young age) because of the appreciation and low multifamily volume.

If they are VERY professional, they will have their processes in writing as verification that policies are enforced equally and fairly by their entire staff.6.

All shapes, sizes, ages, etc. 

Suburban age?

It’s a proactive step that helps avoid costly surprises during construction and ensures that the ADU is designed with a full understanding of the site’s topographical nuances.A Building Verification Survey (BVS) verifies that the ADU is accurately placed on-site in relation to the property lines and in accordance with the approved plans.

Ask local property management companies what they are seeing for utilities for similar fourplexes.I don't know the age of this building but mine are 80s built.