Integrating other CMS into WordPress

I’m not quite sure if I’m asking the right question or what, but I’ll try my best to get my point across.

I use WordPress 3.4.2, I also use SMF 1.1.15 (a forum), and I use a Web store, Lightspeed 2.5.0. My question is what’s the best way to link these all together? At the very least, I want to have the navigation bar/header that I use on my WordPress site to be on the top of my forum and web store.

At best case scenario, I would want to be able to have web store and forum, within my WordPress page template. i.e. I have a template for the web store on my WordPress, and within the posts, I call out to my web store folder so that the content is my web store.

Does that make sense? If anyone can point me to the right reading material, if it’s too complicated to explain over a post, that would be a huge help. Thanks so much!