Re: Painting lap siding
I would use a 3" corner roller. You can get longer one, though a 3" is most versatile for all types of painting.
A corner roller has the roller nap rolled over the end so that it paint's both the flat and the vertical at the same time. It also forces paint down into the corner. At the very least you can use the roller to get the material onto and spread around on the wall, then use a brush to lay it off and make it pretty.
I would recommend the use of scaffolding to be able to do larger areas at a time. It's fairly inexpensive to rent, or you could stretch a plank between two ladders, just make sure those ladders are set properly and firmly.
I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!