1. Now or in secondary. Will get more Brett character if pitched earlier.
2. Just like any other starter. Not necessary if not using it as the primary yeast.
3. Leave it in primary for a few weeks. The Brett should be in suspension, so you will transfer it to the secondary.
4. Not necessarily. It makes the pellicle to protect it from O2. If there is no O2, there may not be a pellicle.
5. No, but you should not disturb it otherwise.