These all sound good. I especially like "New tab before/after this tab," "Height/width settings for selected/unselected/all tab(s)," &, I think, "Send tab to a certain position," though I'm not sure how it would be implemented. (I'm not a developer.)
I don't quite understand what you mean by "Color the toolbar with the color of the current tab." Actually, I have a couple of layers of toolbars.
ColorfulTabs is a fine product that I've been using for years; I'm sure any changes you decide to make will only improve it.
Thanks!