One way to help either screws and nails penetrate wood without splits is to use beeswax on the fastener. In fact, some carpenters will drill a hole in the end of a wood hammer handle to fill it with beeswax. An alternative is to buy a wax seal for a toilet. It's made of beeswax processed to stay soft, and costs much less.
Since roofing shingles are brittle in winter, they may break if you handle or walk on them. This makes spring a good time to do an inspection. Look for loose or curling shingles.
One of the most important things to be aware of is that paint is formulated for either interior use or exterior use, and they have different properties: Interior paint is formulated for: Scrubbability and stain resistance; Good hiding ability; Splatter resistance; Easy touch-up. Exterior paint is formulated for: Color retention; Resistance to fading; Flexibility to withstand expansion and contraction due to weather; To provide a mildew resistant coating; Resistance to tannin bleed. Don't think that you should use exterior paints indoors on the assumption that it is "tougher". In fact, some of the highest-grade exterior paints can be worse to use indoors than a lower-quality interior paint.
To sand coves, wrap sandpaper around small lengths of clear flexible plastic tubing. Most hardware stores carry this type of tubing. Choose a diameter smaller than the radius of the cove. Slice the tube down its length and slip one edge of the sandpaper into the slit. Then wrap the sandpaper around the tube and hold it tightly.