EU Settlement Scheme - non-EU spouse joining from abroad

I'm a non-EU national currently living and working in (Republic of) Ireland, and I will be joining my EU husband in 2020 after my job contract is finished. He has been granted settled status. I was a resident between 2016 and 2018 on a Tier5 visa, so I have an NI number and a UK bank account.

I'm trying to get all my ducks in a row to reduce the stress of the whole process from start to getting a pre-settled status.

My understanding is that I should apply for the EU Settlement Scheme Family Permit, and assuming all goes well and this is granted, I enter the UK with that. Since I will likely be entering by flying in from Ireland, there are no checks at the borders -- do I need to 'activate' my EUSS Family Permit so to speak, by going into the UK through a route that has an immigration officer?

There seems to be not enough information for the transition between the EU Settlement Scheme Family Permit to the pre-settled status for spouses or family arriving from abroad:

1. Since the family permit is for 6 months and I need to provide 6 months of proof of residence, what are my rights / legal status in the UK in between the submission of my application and getting the CoA? I understand from other posts that there's usually a gap between submission and getting the CoA.

2. Will I be able to start my pre-settled application a few days or two weeks before the full 6-month residency mark, or would it need to cover exactly or more than 6 months for the proof of residency to be valid?

3. What are my limitations while on the EUSS Family Permit? Would I have the right to seek employment, use my previous NHS number and register with the local GP, etc in the UK while waiting to be eligible to apply for a pre-settled status?

4. Is there anything done different when applying for a pre-settled status after holding an EUSS Family Permit? Will I have to go through another biometrics appointment for the new BRP card even though the EUSS Family Permit application would have my biometrics already on record?