First off, you're not stupid at all. You did decide to try vaping, which shows you're quite intellient!
The iStick 30w is a good, reliable mod. I use that myself for my backup. It looks as though that setup there has the Lemo2 tank on it, but I can't be 100% certain. Subtanks are basically any tank with sub-ohm capability--this means they can handle coils below 1ohm. But you also have to make sure your battery can push it. The iStick 30w can; it can handle 0.4ohms and above (up to 3.0, I believe).
I've also heard rave reviews about the Cool Fire IV, but I've never had one so I can't really say either way.