MacOS – How to make Command+Tab only bring the active window for an application to the foreground

control+F4. Cycles through the applications in that Space.
(I actually have this mapped to control+`; which I find easier to remember, being close to the cmd+`; to cycle through an application's windows.)

To change the keyboard shortcut, go to the Keyboard preferences, Keyboard Shortcuts, and Keyboard & Text Input. It's the 'Move focus to active or next window' option.

(Edit to fix the keyboard shortcuts; I didn't realise that the backtick character wasn't showing up.)

I'm afraid you cannot do that, since the Dock (where this menu belongs) cannot be distinctly used on each space.

But, what it might be handy is to disable the option:

"When switching to an application, switch to a space with open windows for the application" from System Preferences > Expose & Spaces > Spaces.

That way, even if you select an application which is not present in the current space, you wont be moved to that space.

After all its just a matter to get used of it. After a while, even you'll be ok with it or you'll just deactivate spaces at all (the latter happened to me).