Hey there, as you probably already know there are tons of CMS solutions out there, and the short answer is: Yes - joomla can be made to support all the features in your list, but doesn't provide them "out of the box". My usual approach is, for low content sites I usually go for Wordpress, for sites like yours I would probably recommend Joomla.
I'm wondering though, how big an eCommerce and forum solution do you need? Both ZenCart and PhpBB are really great stand-alone components which can be bridged with Joomla, but there are "smaller" alternatives that plug directly into Joomla, such as Kunena ([http://www.kunena.org/) and my favourite NinjaBoard (Light weight, that adapts to your Joomla theme) [URL="http://ninjaforge.com/extensions/ninjaboard"]http://ninjaforge.com/extensions/ninjaboard](http://www.kunena.org/) , being forums and I'm sure there are eCommerce solutions too.
All in all, yes Joomla can do all of the things mentioned in your list, so can other CMS solutions, but before you start putting stand-alone components together, check out the extensions for Joomla and see if they suit your needs.
Hope that helps,