How to setup my site directory structure??

[Katelynn]

First off .. thanks to everybody that has helped me in the past! My site has over 10,000 Members and we have over 1,000 Members & Guests (avg) online at any given moment.

My current community is setup like this:
- vBulletin 3.7 installed in the "mysite.com/forum" location
- vbAdvanced setup as the root "mysite.com" location
- redirection from "forum.mysite.com" to point to "mysite.com/forum"
- the only affected MOD will be Video Directory Remix (not updated for 4.0)

I want to upgrade to vB 4.0. Just moved my entire community (2gb worth of information) to a new VPS server! I would like to set it up for optimum functionality and SEO. I already purchased the 4.0 vB Software with Publishing Suite.

So my question is .. what is the best way to set this all up? I guess now would be the time to make changes? I am wondering if vbSEO is needed? What other SEO efforts should I be making? Lots of questions on SEO!

As for setup? I would like to see something like this:
When you go to the main page "mysite.com" you see TONS of content, provided from the vBulletin blogs, posts, articles, etc. I am also going to install clipshare as well (since Video Directory Remix isn't updated for 4.0) and need to figure out the best location to install that?

So ideally, structure wise I would like to do:
mysite.com - CMS from vB? .. is this possible?
mysite.com/forum or forum.mysite.com - vB Forum
mysite.com/videos or videos.mysite.com - Clipshare

Would this be the best way?? How would I go about doing this? Does the new vBulletin eliminate the need for vbAdvanced and allow CMS to be posted to the front page of my site?

SEO is a big concern obviously.

Thanks everyone for your help and guidance!