If you don't use any of these keyword, then please do not present yourself as a C++ programmer at all. Some are quite infrequent - I've never used "auto", "register" - but I can't think about any serious C++ OOP code lacking "explicit".
I am not a good or a professional C++ programmer by any means, but still I find these quite basic. I think you will encounter them in the first 5 items or so of Meyers.
Has anyone here actually seen (or written) C++ code that used the <i>and</i>, <i>not</i>, or <i>or</i> keywords (from iso646.h)? These keywords seem cleaner and are standard, yet I have never seen (or dared use) them in practice. In my day job, I write code that must be portable across a dozen platforms, so I am paranoid about using "unusual" C++ features.
Kind of reminded me what a gigantic, arcane mess C++ really is. It's not enough that there are half a dozen different semantics of "const" -- the "mutable" keyword let's you break the convention of the const function (not changing member values) without a user of your interface ever knowing about it.