We have been using a DAP product called Fast'N Final for years.
It's got vinyl in it,and seems to bond to the PVC better.
Make sure it's for Exterior.
Apply it a little "proud" of the hole or repair,then sand it smooth.
I like to "spot prime" it with an alkyd primer,although DAP says it's not necessary,
but it makes for a better finish.
As for painting,
for years we used a primer called "STIX",that's supposed to bond to anything.
But I could take my fingernail and dig right down to bare PVC.
Last job we used a Benjamin Moore primer that really stuck.
Can't recall the name,but the guys at the store recommended it over STIX,and it works.