Primary residence acquisition, renovation and then conversion to rental

[AA76]

Hi:

We acquire our primary residence in 2009. We renovated this property extensively in 2015 converting a single story ranch to two story house. Roughly the cost of renovation was similar to the acquisition cost in 2009. In August 2021 we converted our primary residence to rental after we moved overseas. What would be:

1. Date of acquisition of our property: 2009 or 2015?

2. Cost basis for the property: The cost of acquisition in 2009 or post renovation in 2015?

I could not find any questions on same issue when primary residence that was renovated and used as primary residence before converting to rental. 

[Critter-3]

1. Date of acquisition of our property: 2009 or 2015?

2. Cost basis for the property: The cost of acquisition in 2009 or post renovation in 2015?  Use  the lesser of the fair market value as of the date of conversion  OR  the total cost of the home to date.