Toenailing styles can vary. Some pros like to drive three or four nails into a stud, toenailing from both sides at about a 30-degree angle. The job is easier if you first drive a holding nail on one side of the stud, then drive two nails on the opposite side. Remove the holding nail, then toenail the second side. You can also make up a 2x4 spacer to place between the studs.
Paint walls from the top down. If you are using a roller, start by making a large “V” or “W” (3’x3′). Then fill in between the gaps, blending into your initial stokes. Always work from the unpainted into the painted area.