Putting the pieces of the puzzle together
 

Hey everyone. I am a aspiring videographer and making the switch over to the DSLR world with a 7D. I previously had a JVC HD7 but it died and am upgrading now.
My question is, I am new to the modular world of camera set-ups. How do I know that everything will fit together if I order the pieces from different manufacturers. Matte box from here, Follow focus from there and so on. What rail size should I get? How do you suggest I build my rig? Or should I get everything from one company? I am looking for a shoulder rig that has a FF, MB and something that has a quick release plate so I can go from shoulder to tripod with ease. I also have a glidecam system that I would like to also be able to easily use as well.
I would like a simple clean but effective rig for a decent price. I really like this setup but I want a shoulder mount.
http://www.visualcinema.com/IMG_2773.jpg

This is a while new world for me and I appreciate any and all advice you have to offer.