Is oil based wood sealer used when painting?

Hi, My next door neighbor hired a contractor to paint his side of our concrete wall (sharing) last year. The final result is very smooth and I like it. While the contractor was doing it, I was watching. He pressure washed the walls and then he sprayed the wall with about 2 coats of paint. I think they did the entire job (around the house) in a total of 3-4 hours, including cleaning the wall too. I have asked my neighbor if the contractor used a self leveler or some type of filler? He does not know. How can achieve the same smooth result without mortar grid lines? I would like to do it by rollers since I don't have an air compressor for painting. Thanks

I need to stain my deck. There is a good amount of wood siding and screen porch 2x4 meeting the deck. Is there a painters tape that works well on such rough surfaces? Also, don't want to strong of an adhesion otherwise I pint the siding...