Upgrading to JCW brake callipers on F56 Mini Cooper S

I have a Mini Cooper S 2017, looking to upgrade my brake calipers to JCW ones.

1) do I need new brake discs or will the calipers fit on my current discs?

2) does anyone know roughly how much it will cost to get the new brakes coded in by Mini/somewhere else around London?

3) will I have any issues with coding if I am only upgrading my front calipers (not rear)?

Thanks