Re: Howto : put a picture between header and content
There are any number of ways you can do this using CSS positioning (and developing your own bespoke website theme).
This isn’t really a BuddyPress question though, it’s a general website development / CSS question. I suggest a good book on CSS would be a starting point.
Incidentally: There’s no need for div wrappers just to position an image (you are adding unnecessary bloat), and I’d certainly avoid inline style definitions (which can be a maintenance nightmare).
@pcwriter – I’m not sure what you are trying to write with your CSS, but I suspect you’ve confused absolute and relative positioning. For the approach you are suggesting, you should make your main header div relatively positioned, and use absolute positioning on your image to position it absolutely in relation to the header div: http://css-tricks.com/absolute-positioning-inside-relative-positioning/
As to suitability of BuddyPress for a ‘simple site’ – it depends what you want that site to do – if you want user profiles, messaging, groups, activity streams, etc. – then BuddyPress gives you a great platform to build on.
If you just want a simple content management system with posts, then you’d be better building on vanilla WordPress.
If you don’t need content management, then your simplest site would just be HTML and CSS.