are all options available in all child themes?

[Cemlyn]

HI. I'm a newbie!! I say that to try and put up a bit of a screen if what I ask here seems stupid to some.

I'm a little confused. I have gone through a number of different sites reviewing the Genesis theme and the various Child Themes. I have looked at the demo of very one of the Child Themes. I notice in some demos that they show an advertising box, sometimes more than one. In others they show none. In some there are colour options, in others none. Can I customize all Child Themes to do whatever I want? Can I change colors in them all, can I add more advertising boxes if I want to. I have the usual dilemma. I like one theme but it shows no advertising and only 1 color, the Themes that offer the right color has no advertising and the one that offers the advertising I want isn't to my liking.

I'm hoping you tell me that I am missing something very obvious.