Looking after it
Wood was alive once and hasn't entirely got over it. Treated reasonably, everything here will outlast you.
The one rule
Never put any of it in the dishwasher. Not the boards, not the bowls, not the coasters. A dishwasher combines prolonged soaking with high heat, which is the combination that splits wood along the glue lines. One cycle can destroy a board that would otherwise have lasted forty years. There is no way back from it.
Boards and bowls
Wash by hand in warm water with a little washing-up liquid, straight after use rather than leaving them to soak. Rinse and dry with a cloth, then stand them on edge so air gets to both faces. A board left flat on a wet worktop will cup.
Re-oil when the surface starts looking dry and pale rather than warm, which is usually every month or two at first and then a couple of times a year. Food-grade mineral oil, which is what I finish them with in the first place. Wipe it on generously, leave it twenty minutes, wipe the excess off. Some of my boards also come with a finishing butter that can be re-applied periodically.
If a board picks up a smell from onion or garlic, half a lemon and a scatter of coarse salt scrubbed over the surface deals with it.
Furniture
Dust with a dry or barely damp cloth. Re-oil a table top once a year, or whenever water stops beading and starts sitting flat on the surface. That's the finish telling you it's thinning. Same method as the boards.
Keep solid hardwood out of direct sunlight where you can, and away from a radiator that's on all winter. Both will dry it out unevenly and can cause movement. Wood expands and contracts with humidity through the year; a small seasonal gap opening and closing at a joint is normal and not a fault.
Pens
Almost nothing required. Keep them out of a hot car, don't leave them soaking in anything, and if the finish dulls after a few years a rub with a little wax brings it straight back.
Marks, dents and time
Let them. A board that's been used looks better than one that hasn't. Deeper knife marks on an end-grain board sand out with 240 grit and a re-oil if they bother you, though most people stop bothering after the first year.
If something goes wrong
If a piece splits, a joint opens or something turns up damaged, tell me.