They will not be able to breed at 9 weeks - and I would advise not seperating them as soon as you get them as they will be very very stressed anyway with the change of housing, loosing their mum and siblings etc.
Keep them together at least at first - you have about 2- 3 weeks before his testicles drop - poss more in some breeds - and even then she will not be fertile at that young age (until about 4-5 months).
However once his testicles drop he will start to bother her - so you may need to separate at that stage.
If neutered as soon as they drop the separaton time should not be as long - so probably juist 3 weeks separate and then they can go back together - but do rebond with care and slowly!!!
She will need to be neutered at c5-6 months. This is essential for health reasons (uterine cancer).
I would suggest you keep them separated only by mesh during the 3 weeks so they are in contact.
Best piece of advice ever for a new rabbit owner: Get a GOOD rabbit vet lined up. Most vets are actually very untrained in rabbit health and care and finding a recommended rabbit savvy/'exotics' vet is an essential that will eventually save you time, money, and very possibly your rabbits life!