Clarification on incentive behind Proposing a Block/Building a Block

On reading through the Beacon chain documentation for the Merge there are a couple of questions I have.

  • Is there any incentive for being a block builder/ what are your rewards calculated from?
  • Is the reward for a propser = base_reward + (base_reward/proposer_quotient)?
  • Is the proposer randomly selected?
  • Does the lead attestor claim there rewards by simply putting a block header on the block?