Benn, a wax over a sealant is actually a very common thing to do and for winter protection something I would highly recommend to ensure your LSP lasts the winter, along with looking good also The wax adds the depth to the finish, something a sealant doesn't. I am actually trying to confirm whether FK1000p is indeed a sealant as I have recently been told it possibly contains Carnuba. Awaiting an answer from FinishKare about it but it may actually be a Hybrid wax as opposed to a sealant.
I would not be applying anything over Cquartz UK other than Car Pro Reload.
Depends on the LSP, Cquartz Uk won't require anything on top of it as that is designed to add 1 µm ~2.5 µm to the paintwork. Reload is a nice finishing touch on it and can help keep it topped up.
Its completley different to the likes of FK1000p, have a read about it. It contains ceramic particles which you find in glass so it adds its very own extremely durable layer on top of the paint. If the car is mint when applying it will add its own extremely glossy/highly reflective layer.
Plenty of people talk about using waxes over the top of FK1000p with no issues at all. I would add wax on top of that product myself.