The safest way to start the claying process is to chemically remove as much of the iron contaminants as possible with a product like Car Pro IronX or Optimum Ferrex. Every car is different, but after iron decon as described above, it shouldn't be necessary to use anything but an ultra fine clay on a new car. Whatever the latest equivalent is to Sonus SFX ultra fine clay...I'm sure there are many.
These days a lot of people on here like nanoskin sponges or towels in lieu of clay. Same function. These products have pros and cons compared to clay.
Klasse AIO is very easy to use. It has a chemical cleaner in it which can be use useful for any remaining contaminants. On the downside, it has very little in the way of abrasives to remove any scratches or minor swirl marks if the car has them. If it does, I would recommend something like Blackfire SRC Polish or Menzerna SF4000 instead.
Klasse SG can be finicky, but if you have applied it before, it's not too bad. There are dozens and dozens of great sealants out there these days, all are pretty good. On this forum, Blackfire Wet Diamond Sealant gets a lot of praise and rightly so (looks great). For ease of use, I really like Prima Hydro MAX. For durability, I would choose a coating like Optimum Gloss Coat. You will get dozens of other recommendations.