Well, as long as the modules are plugged into power correctly, there shouldn't be an issue. Knowing about the red-stripe is day #1 knowledge. Getting your modules plugged in is very easy to do. It's also very easy to plug something in backwards if you're not paying attention and get over-confident.
It looks like your case is full. So after you've explored what you have and how it works, I would say the next evolution is to transplant your modules to a bigger, more useful case. The Tip Top Mantis seems to offer the most value for the money from what I'm seeing. You'll have lots of room for expansion.
As far as exploring new modules, multi-feature modules are great. The Swiss Army Knife type usually allow for exploration in functionality. The big three I can think of are Pamela's New Workout, Disting EX, and Ornaments & Crime. There are others that are nice to have as well. In my opinion, you'll probably keep these three modules as there always seems to be an application for them and for the price (less than $1000US) for all three, you'll get a LOT of use and learn a lot from them.
I've mentioned the big three in other posts. I hate sounding like a broken record. But the questions seem to be the same. :)