I am still trying to comprehend the tighter integration between forum and website. So it could well be I am making some wrong assumptions here,
When I look at this screenshot:

Weird, will test it more, also i will update the demo forum so that we can get a better understanding.
Aren't the large buttons more suited for the website, and not for the forum?
If you opened the forum page, there are already boards called "latest version", "Questions" etc.
I am a bit confused what these large buttons would add to that specific forum page.
I am trying to not only integrate the function, but the look as well. Also yes, the latest version board is still there, but this should take the user directly to the download page, instead of opening the board then opening the latest topic THEN scroll to the bottom to see the latest update.
Providing the latest version info at the top means you can quickly check if your musicbee is updated or not, instead of either scroll to bottom or going to download page.
Also the second box is much more of a reminder to new user for addons, you can call it Promotion AD(:{)
the third box is something special which is COMING SOON! you guys(or maybe gals) will LOVE it

About the top-bar. Is it intended to be similar looking, whether you are on the website, or at the forum?
Not having a strong opinion on that, but if so, maybe it could be made slightly clearer where you are at that moment.
Either by having a slightly different color design, or maybe by having the tab 'FORUM' highlighted when you are on the forum.
I think it is pretty clear where you are, BUT menu highlighting is COMING(i have planned this already

)
And about the 'HOME' button at the top. When you are navigating the forum, is that supposed to take you to the main forum page, or to the main web page?
YES, with smf version 2.0.11, they changed the forum navigation system! so i still haven't figure out a way to rename it to forum home, like i did with the previous one :S
i will look into it in FUTURE!
ALSO, as for the concern of that big boxes at the top, i will include a button to hide it

it will use cookies to store the preference and stay hidden when the next time you open the browser.