Also, just to make sure, these are all the sibilants of the Russian alphabet right?

ж, ц, ч, ш and щ

з and с are not sibilants or am I wrong? Because I never see them included in any sibilant lists.

And all the velar consonants are г, к, and х right?

Or are there any more?

I'm asking because I want to be as thorough and complete as possible.