Wild areas

Often, yes. Many servers regenerate the wild on a schedule to refresh caves, trees, and structures. Any builds there should be treated as disposable unless the rules explicitly say wild builds persist. Some servers go further and discourage building entirely in the resource world.

On a lot of servers, yes, either officially (PvP on) or practically (unclaimed space where conflict happens around spawners, routes, and limited resources). Even with PvP off, the wild is where you run into strangers and get contested through competition, traps if allowed, or theft if the rules permit it.

Plan for a bad death. Bank often, use an ender chest if the server allows it, and move valuables in smaller trips instead of one huge haul. If there is a nether hub, learn the lanes and exits because it is usually the fastest route and the one most likely to be watched.

Sometimes, but many servers block claiming so the region can stay open and reset cleanly. If claims are allowed, they are often limited in size or treated as lower-priority for enforcement. The safe assumption is that long-term bases belong in claimed space, with wild outposts kept small and replaceable.

Bring gear you can replace, food, blocks for bridging and towers, and a reliable way to navigate (coords, landmarks, or a lodestone if enabled). If PvP is on, prioritize mobility and escape tools over perfect armor early on, and avoid carrying everything you own.