Plates you want aren't taken forever. Here's how they come back, and why catching one takes luck or a lot of checking.
A taken plate usually comes back when the owner:
States typically hold a dropped plate for a while before anyone else can order it, so the previous owner has time to renew. How long varies from state to state, and most don't publish an exact date for any given plate.
There's no announcement when a plate becomes available. It just starts showing as open on the state's lookup, and the first person to order it gets it. Short and popular plates can be gone within days.
The only way to be first is to check often. License Plate Scan rechecks taken plates on a schedule and messages you on Discord when one opens:
It depends on the state. Most hold a dropped plate for a period so the owner can renew, and don't publish exact dates.
Generally no. You can only order it once it shows as available, so watching it is the best option.