Lived in it for 2 years and bought a bigger house and have been renting for the last 10ish years.

We know being an landlord is a job, but if we hold it for long time, it can be a decent income.However, now we are thinking since the interest rate for our sfh is 6.375%, why not sell the townhouse and pay the principal of sfh?

Entitlements go a long way towards lender comfort as well. 

., Canada, and Latin America, 38% expect to expand office space over the next three years, up from 20% last year.

Last week, she called saying that the kitchen flooring has holes in it and she tried to put tape on it but now shes dealing with a pest situation and they are going in those holes.

Tenant paid last month ~ 20 days late, and short paid, and still hasn't paid this month (it is now the 21st), so they are basically 2 months overdue.  

Long term goals - My husband and I have set a goal of 5 units per year.

Legally, in Alabama how long after missed payment can I do a pay or quit notice? 

That 10% below market value is what I've commonly seen the last couple years.

You seem to have met the standard of the statute since ypu sent notice to the last known address.