Google colab - compute units

Hi all,
Google colab pricing is now tied to what they call compute unit.

Could someone please clarify the following?

  1. Relationship between 1 compute unit and GPU allocation on colab.
  2. What does it mean to spend a compute unit in terms of disk space / cpu cores / gpu with respect to time?
  3. Does network transfer outside the google data center, say, to my laptop consume compute units?