My view is that all the upgrades you have listed are worth doing and almost in the order you have listed them, particularly with your planned longer touring in mind.
Phils Centa mods are certainly worth doing as you are planning some longer trips, a broken Centa will finish your trip. It also smooths the transmission.
I would do the G56 exhaust first and then see if you feel the cost of 569 cams and the unlocked ECU (that may be getting difficult to obtain) is worth it. The car will go and drive much better with the new exhaust and filter. The standard ECU will adapt with Stage 1 parts fitted but not the 569 cams.
The Ohlins get good reports but there are alternatives that are cheaper and (almost) as good. The ATR's are certainly good and about half the price. The adjustable Spax are a noticeable improvement over standard. With all the adjustable shocks you can adjust the rear end ride hight for load carrying, a consideration for touring.
The Empire steering kit is an improvement but not dramatic. I have it but I got it when there was no Comfort Kit available and bump steer was the thing. If my car had been like a 2020 car for it's steering, I would probably have been satisfied.
Phils BB mount is good and solves all the NVH issues but several M3W's I have driven with the NVH kit drive and ride very well, some not so well for some reason. If your car is one of the better riding NVH kit cars, leave it as it is.
