HI Srlkar,

Yes you need to reduce it with a DT reducer - DT 870 should be fine - you can get the DT reducers in quarts and gallons. You can also use it with Concept and Clear.

You can reduce the primer up to 50% and use either the west systems foam roller or white foam rollers that you can get at the local hardware, they are for trim detail painting. It's easy to apply and sand smooth starting with 220. Block sand till you start seeing high spots that come up thru the primer, that is how you gauge your coverage and thickness.

good luck and happy priming

dean