And use a stain block paint. I only used a standard primer and the knots are now showing through.

Use a white tinted shellac on the knots best primer for that problem

believe it or not, it kind of depends on what state you live in. I good primer like Kilz and a really good oil-based paint would look great...however, you can no longer buy really good oil-based paint in California anymore because of the air quality restrictions. I painted a stone fireplace years ago (in CA) and it took coats of primer and just sucked it up. I finally got tired of it and painted it with a good oil-based white and it finished the seal and provided a nice finish...has been at least 20 years

Wash down walls with TSP, primer with Zinsser 1 2 3, then paint. The prep work is what makes the job last. Just do one room at a time. Although if there is a room you want to keep naturally paneled, then just paint the trim a soft white, which provides a lovely casual look.

If you want to minimize seams, after all of the cleaning. fill seams with premixed drywall mud. once dry, sand lightly to smooth, prime and paint. Mine look smooth with slight texture.

Thanks All!