If you're wholesaling residential properties, keep in mind that most property owners will also be speaking with and meeting local investors and realtors.

For residential multifamily properties (1 - 4 units), can you use a home warranty to take care of the repair costs associated with rentals?

If you can find a place where the HOA or COA is flexible and you are able to convince the membership to go into development and perhaps convert the property into a co-op you could build a new apartment complex with commercial rental spaces on the ground floor and residential spaces on the top. 

My mom is a landlord in LA and relies on rental income from a few small residential properties.

All being equal, I would take a 30, but sometimes the 15 is much much lower.In 2012 I refinanced every residential mortgage I could as rates dropped to the lowest in 50 years. 

Enforcing the termination of a lease due to non-compliance (unauthorized resident) is not the same as ending a month to month lease. 

The market I’m interested in are residential rental and leasing, senior housing, and distressed properties/owners. 

What is the realty of converting a new Warehouse build into apartment spaces?

Are you searching for residential or commercial developers? 

Tenants will push and try to get everything they can from their landlord.Seems you've done everything possible to be reasonable, yet the tenant is not satisified and wants more.As already stated, you are too much of a pushover, so the tenant is seeing how much farther they can push you.Highly advise you to find an experienced residential landlord-tenant attorney ASAP.