Forum Moderators: rogerd
There are different ways of approaching this "total site" approach. The one you checked out is starting with a CMS and integrating features. Another approach might be to start with powerful forum software and use "portal" addons to round out site functionality.
VBulletin, for example, has a few popular portal hacks (vbindex is one) that let you create a separate home page with various content. Some of the features you describe, like user authentication, polls, etc., are built in already. You might still need some custom coding, but I'd guess this kind of solution would get you a lot of what you are looking for.
A lot depends on how important the forum will be - if its a minor feature, you may want to go the CMS route; if you expect it to be the focal point of the site, then starting with forum software and building out may make sense.