Some good advice here and the best is to go to some of the knife forums and read about the different qualities of steel used in knives. One thing that I found in doing some research is that about all of the top quality knives use pretty much the same steel with some minor variations. Just think about what you are going to use it for and how you are going to use it.
You question about whether to get carbon steel or stainless steel makes me smile in a way. I understand what you are talking about but a question like that could create all kinds of arguments those want to be technical. Ask yourself, where on the periodic chart of elements does steel fall and in which country is the majority of steels mines located? When you figure that out you can decide which type of steel is better.
I have a Buck 110 knife that I always carry with me when working outdoors and a Buck Knight that I carry with me all the time. I also have a couple of Kershaw knives that are excellent but I find the metal handles a little slippery. In my total collection of knives I probably have well over 50 but the two Bucks are my favorites.
War to the Knife, Knife to the hilt.
If we don't want to live in a trashy area, we all have to be willing to help pick up the trash.
You answered the questions correctly and it was just a point that I was trying to make that steel is always an alloy of metals usually iron and carbon. Stainless steel usually contains chromium along with iron, carbon and possibly many other metals such as nickel. The questions were just an exercise to get one to realize that there is much more to it than just saying carbon or stainless steel.
Usually the harder the steel the better it will keep and edge but also the harder it is to sharpen and more brittle it is. This is not always true but there are many factors to consider. I have no idea how many different "official" types of steel there are out there but I would say hundreds if not thousands and each with distinct properties. As you say cost is one consideration. Then you add into it the blade shape and edge grind it gets so confusing until you don't know what to choose.
Are knives really "less lethal"?
Like everyone's said, as a rule carbon's sharper, and stainless is lower maintenance, but there's a huge amount of variance, and lots of steels that are pretty good compromises between the two - AUS 8 for example. Most knives from most reputable manufacturers are going to be pretty decent.
For a folder I prefer stainless. For a survival knife I like high carbon. because in a pinch you can sharpen it with a rock and use your flint with it