Congratulation on the new boat, it is a beauty, I saw it at Baert before it shipped out to you.
For my cushions I simply stay on top of them with my normal boat soap, the trick being stay on top of them and don't let them get soiled in the first place. I use straight boat soap and a brush at the end of the year which really cleans into the pleats. I also use the 3M upholstery cleaner/protectant about twice a year and when I do get a stain.
That said I also had a cover made for mine that goes from the windshield back over the seats and connects in the cockpit just aft of the seats. The cover uses only existing snaps and has made a big improvement in reducing the beating that the seats take in the weather and day to day assault by the seagulls.
Enjoy the boat.