Questions about storage rent

My understanding of rent is that every epoch (3 days i think), a check would be made for the account balance and if the balance is lower than 2 years worth of rent, rent is deducted per byte.

  1. How is the number “2 years” determined, is it arbitrary?
  2. If I withdraw funds just after the rent check and deposit back just before next rent check, will the system detect that?

Link to answer in discord here!