Bat 21 - the forum module is available - but if you do a search on the issues people have with the forums, then I suggest you use the free ones from http://www.activemodules.com - honestly - you can't compare the two. The gallery module is the same in DotNetNuke.
I've got YAF running on another site - it's pretty good actually for what you get for nothing. There's also http://www.presstopia.com - which I had running on http://www.catalooksupport.com - which was a slick little module but I think I outrgrew it's functionality so installed the Free version of the http://www.activemodules.com instead.
The problem I see here, in general, is the time it takes for the base dnn installs to get fixed, in fact we strip out and remove everything except the base dnn install, and then look around and add in the very cheap or free third party solutions which are provided by many community members here.
What you'll find is they tend to support their products better than what you'll get here due to the nature of this project.
The down side of this is - if you install a third party - (eg. someone else's) module - you run the risk they could do a runner and never be seen again but you're stuck with this produc that can never be upgraded again, which is why someone like http://www.activemodules.com is a good solution since he's well into the 'key module developers' environment.
But the down side of using any of the extra dnn modules that are part of the project is they take forever, if ever to get updated - the gallery module - years, literally years before anything has been done and released to the public.
The forums module - a huge job, but years to get right - and it's still got complaints from people here who say it's never fixed or supported.. so there are pros and cons on each side.
I think there is nothing wrong with supporting the good 'base model' dotnetnuke version and then go find some really good solutions that might be free or cost you not much more than the price of a cd and get the benefits of what organised and commercial dnn solutions can bring you.
I've tried in vain to use just dnn modules and found I spent more time reading on the forums why something wouldn't work, and found that once I switched to some of the cool 'third party' solutions, it just worked and I was able to carry on with the work, rather than getting stuck wondering if it was me.. or was there something wrong.
That's my take on it.... so enjoy your journey Bat 21.
Nina Meiers