The question is this (numbers are just round for ease of calculation):  Suppose the home is valued at $500K, and I took a $50,000 (10%) distribution last year, including what was owed for taxes.

If the bill is $100 a month split between four units, increase it to $120 and charge each tenant $30.How to calculate charges.

It goes through the entitlement and how to calculate it.One VA Entitlement to Rule Them All

This one is a bit more involved and I might make a separate post to get more feedback:Let's say before I purchase any house, I have a combined DTI with my wife of 13% (Assuming gross income is used to calculate DTI).

@Dan Hertler You’ll have to start including capex into your ROI calculations before purchasing a property.

If so, how much should we consider, like do we need to calculate by their salaries by hour or how much day/hours spending so they will be deducted from the rent? 

I would use current interest rates and terms for your refinancing calculations in case rates do not decrease.

Would sec 8 decrease the rent to the calculated fair market value of rent or at worst case scenario remain the same and sec 8 decline the increase?

Broker commissions are generally calculated based on the base rent.Ex: $12,000/yr in base rent x 5 year lease = $60,000 -- $60,000 x 5% commission

Take calculated risks, learn from experiences, and build a strong support network for success in the journey.Good luck!