Yes, pressure washing a wood deck can be a good idea as it effectively lifts ingrained dirt, mold, and mildew, improving the deck's appearance and longevity. However, it must be done carefully, as it's easy to damage the wood, especially softwoods. To pressure wash safely, use a lower pressure setting and a wide, 40-degree fan pattern nozzle (often white). Keep the nozzle at least a foot away from the wood surface and maintain constant motion, avoiding hovering in one spot to prevent gouging.

You can build an outdoor kitchen on a deck, but you should choose composite decking since it's more heat-resistant. Metal deck materials like steel and aluminum are also good choices because they're less flammable than wood. You should also consider the weight of the kitchen—make sure your deck can support it and any appliances you plan to use. You should consult a structural engineer to confirm exactly how much weight your deck can safely support when building an outdoor kitchen. 

To flatten a cupped deck board, start by ensuring it’s dry. Then, try flipping the board over so the cupped side faces down and reattach it. If that’s not possible, you can use screws to pull it tighter to the joists or plane the edges slightly to reduce the cup. It’s best to replace severely cupped boards.

You should refinish your deck to maintain its appearance, durability, and longevity. Refinishing your deck protects the wood from foot traffic and the elements. It also helps extend its life span by keeping rot, mildew, and termites at bay. By maintaining your deck, you can avoid the cost of replacing your deck sooner. A refinished deck also looks great and restores some of its original beauty.