Stake pools are run by stake pool operators. These are network participants with the skills to reliably ensure consistent uptime of a node, which is essential in ensuring the success of the Ouroboros protocol and the Cardano network as a whole.

The protocol uses a probabilistic mechanism to select a leader for each slot, who will be expected to create the next block in the chain. The chance of a stake pool node being selected as slot leader increases proportionately to the amount of stake delegated to that node. Each time a stake pool node is selected as a slot leader and successfully creates a block, it receives a reward, which is shared with the pool proportionate to the amount each member has delegated. Stake pool operators can deduct their running costs from the awarded ada, as well as specify a profit margin for providing the service.

Delegation is the process by which ada holders delegate the stake associated with their ada to a stake pool. It allows ada holders that do not have the skills or desire to run a node to participate in the network and be rewarded in proportion to the amount of stake delegated.

Yes. Delegated stake can be re-delegated to another pool at any time. Re-delegated stake will remain in the current pool until the epoch after next (from the point of re-delegation), after which your delegation preferences will be updated on the chain and your stake moved to the new stake pool. Rewards are distributed from the end of each epoch, so you’ll continue to receive rewards from your original stake pool for two epochs before your new delegation preferences are applied.

This is not a legal advice: Tax treatment is different in different countries. In Australia the current expert opinion is that staking rewards are handled like purchasing new crypto. After one year the can be sold without taxes. Before one year they need to be considered as additional income and needs to be considered with your personal income tax rate.

Your funds are not locked. You can use them at any time.