Ok so still fairly new to the hobby,
1, can drones leave units and wander off or join other units I.e. a grab inhibitor drone leaving pathfinders and joining strike team?
2. If I have 6 gun drones attached to a crisis team and the suits advance, do I roll a separate dice for the drones or do they all advance together off the suits advance roll?
Appreciate any help
Drones don't "can" leave units. After deployment Drones are automatically their own unit.
For example if you buy 2 Shield Drones and a Grav Inhibitor Drone and a Recon Drone for your Pathfinder, you deploy them together with your Pathfinder unit and from then on you'll have one Pathfinder unit and one unit of mixed Drones.
As above, they form their own unit after deploying them (if you put them in reserves, both arrive as one unit and seperate afterwards).
So yes you roll seperate dice for the Drones and the Crisis since they are two completely individual units at that point.