passport renewal while waiting for work permit (Nairobi)

Hi all, I need your advice...
I have applied for my work permit in Nov and now the status on e-FNS is 'approved' as of 13 Jan but not 'issued' yet. While waiting for the permit, I realized that I have to renew my passport soon as it will expire in early Sep and Kenya Immigration requires foreigners to have passport with more than 6 months validity.
Renewing my passport in Kenya is not an issue but my concern is that the permit application is made with a current number.
Could you please advice me:
1. how long did it take for you to get the permit issued since it is approved?
2. anyone has renewed your passport while waiting for work permit?
3. anyone has renewed your passport and transferred the permit endorsement to a new passport? how it works?