I would add DON"T spend $100 on the kit. Wait for a week with the one day 50% coupon.
Also, yes it is mainly for buttercream, but it also is aimed at those taking the class. Some of the things are completely unnecessary. Icing tip caps...oh, please. A wet paper towel keeps the royal icing from plugging better than those silly caps.Spatutlas
... they are metal and come in angled, straight, tapered, and are used to ice the cake. I loved the humongous one because suddenly I could ice the entire top of a sheet cake in on swipe.
A cake level
...the one that Wilton sells is actually a piece of wire that pushes through the cake rather than a blade. It's okay for smaller cakes. I used a serrated knife to get it 'started' and also on the edges that are right angles since the wire will rip the cake apart if you just saw through the cake.
I agree with taking the classes if you can. The ladies who teach them are for the most part in it for the love of sharing the art. Lots of them are on this board, too. Wilton hires them to stimulate sales in the cake aisle. My teacher was honest. "If you really think you'll use clown heads a lot in you decorating, then by all means buy them." ( I didn't.
For a real beginner..and I really was when I took the classes...the method is pretty solid and you get to have someone over your shoulder watching your angle and correcting your technique. You really can't get that from Youtube videos.
Keep asking questions and you have found the right sight to learn all the great tricks as well as be inspired by the amazing decorators who share their work.