How do I set this up the right way, transferring from Wordpress as CMS? I'm trying to do something I'm used to in Wordpress, but can't really find a right way, or 'correct' way. What I was used to do in Wordpress; every page had a few options, like center content, background image, etc. In page.php (if you know Wordpses this'll make sense) I called a function pageDetails() (defined in functions.php) which returned me some variables for centering content, if it had a background image, etc. 

Now I'm trying to do the same in Craft, so I created a section for the pages, added some custom fields to the pages, and now I'm trying to create a likewise method for defining a function once and use that for different 'entry types' to avoid repeating myself for each entry type template. For this, I keep coming back to creating a macro, that I define in _macros/macro.twig (for example). But, I can't get it to return variables.

In short; is there a way to use 'variables' from entry template, to the macro, and have the macro return vars (or array) to the entry template so I can use them in there? Or should I completely rethink this way of doing it?
Macros are intended to output to the page, rather than return data to the caller. If you must return the data, I'd suggest writing a custom plugin (although that's where my knowledge stops!).