Thank you Ed.

I have had quite a lot of conflicting advice on this so far!
I was initially told i could not use the lever on the FE as the isolation valve, but having spoken to james cooper, this is not the case and i am fine to do this.
I will do as you say and add a hand screw to the lever.

The quick release does not hold pressure, so the busrt disk on the FEV would cover the short pipe run to the ball valve, but the de-coupling risk is a good point so I will re think the QRV.
Does everyone else just undo the bottle fitting each time they want to fill/ inspect the bottle?

The reg came with a burst disk so I will just leave it on there. It saves trying to plug up the port too.

Do I need a dump valve directly after the bottle (before the reg)?

Thank you for your help