IMO, old wood (regardless of type) is a pain to work with as it splinters when nailing or applying screws. 

If you do collect the rent (delivered or otherwise) and they have any outstanding previous late fees, apply the payment first to all other charges, if your lease includes that wording.Then give notice and file for eviction for the shortage.At least that is my methodology, as in Texas a property manager can only represent a landlord in court for eviction on unpaid rent and holdover.

Here are the options I thought of based on what I know: 1.)My Father sell the house to me if the house is completely under my Father2.)Apply for a HELOC loan and if approved buy out my family - about 300K (100K each) which has been discussed with them and I would possibly like to take out more (~100K) to purchase either my own property or use it to start house flipping.

Thank you so much for your generosity.I will continue to listen and apply.

The provisions of this article do not apply to:1.

I'm planning to apply for mortgage for the fourth home as primary residence(CA), Will I be able to have mortgage interest deductible since it will be my primary residence?

If the deal is for $140k all cash (and you get $40k right back), you're probably OK. but any half-wit loan officer the tenant uses will see right through what you did, which is to artificially bump up the market history of the property to influence the appraisal and mortgage size the tenant is applying for.

Checked with the city, they came back with no flexibility and that, even with the chance of applying for the zoning change, it would never go through due to configuration of the property.

If they want to apply and qualify then you'll need to accept them unless you have a better qualified applicant. 

It only applies to commercial businesses and multi-family units.