I agree that the walls will be fine with a nice sanding and a prime. A good quality primer should cover the walls in one coat.
I also agree for the wood grain on the cupboards, just think, the pain will be worth the result! For a light stain in any colour mix a squirt of water-based paint (artists acrylic is cheap and comes in any colour you can imagine) with water in a jar, shake well until all the paint is mixed and apply to the wood with a cloth. you want maybe a teaspoon of paint to 300mL of water (start with a little paint and add more as you desire) and be sure to wipe the stain on in the direction of the grain or buff it in with a circular motion. The effect can be as subtle or as bold as you like and you will have a lovely tinted wood as a result. Just be sure to seal the wood with either wax or polyurethane (water-based) varnish.