I have only experience with the security director and I know it can control security features of firewalls only.
1- How to control routing of the firewalls from Junos space? what application should we buy extra?
2- Which application in Junos space we should purchase to manage switches? Is it Network Director?
For switch & qfx then u need use ND and for MX then u need use CSD. Routing part also can be configure under ND/CSD/SD as i remember.
From the ND and CSD can you do the daily stuff like change access VLANs and create LAGs. In the datasheet, it's not clear.