Answers

Try Shewin Williams Loxon XP which is for Masonry.  It lasts a very long time and no need to prime.

All of the premium coatings have been improving the last few years.  Our company uses Sherwin - Williams SuperPaint for the Body and Duration for the trim.  If you can afford duration for the whole house it could be worth the extra dollars. 

The newest thing is that paint has gotten expensive !

Thank you

You need to make sure that the material allows water to pass thru the block or stone.  Both choices can allow water thru if planned ahead.  Blocks can have weep holes that allow water to pass and many faux stone products are designed for drainage. 

Give a place for the water to go -