I designed http://www.crainefrahm.com a while back and it’s a total mess in terms of coding. It uses opencube’s Tree Menu, which isn’t registered so on PC’s there is a "unregistered" warning message that pops up. I finally found a better menu solution with the SBD accordion menu, originally developed for Joomla.
I’d recommend using one JS framework to avoid conflicts. jQuery allows you to use jQuery() instead of the $() to avoid these issues but I’m not sure about Mootools, etc.
Both jQuery and Mootools have a range of plugins that will provide all your needs. So I’d go with just the one. Why load two or three frameworks when you can use just one.
You could go with jQuery if your using Galleria (which is a great gallery plugin) and find one of the many jQuery accordians out there then use jQuerys .load() function to bring in the external pages into the div.