What type of wiring am I?

[Bizman]

Dummy question, but since I bought a pre-built I didn't spec anything out.  Typically do you get to choose what type of plugs/wires you get?  Is this something that comes standard with a PSU?

Yepp, they're standard for legacy compatibility. Also, as someone said, the Molex connectors are often used for fan controllers, either front panel ones or simple hi-lo switches. The smaller one used to be a floppy drive connector, lately I've seen it used for 3.5" front panel card readers.

Your PSU doesn't have coloured wires. If it had, you'd see a pattern: Yellow (12V) and red (5V) on the sides, two black (ground) in the middle. But as Easyscor said, they're shaped so you can't connect them wrong.

[cav58d]

Can I connect three 12v case fans to a single molex, or should every individual fan be connected to an individual molex?

[Bizman]

Fans don't usually use much power compared to e.g. hard drives not to mention video cards. It's perfectly OK to connect them all to a single molex. Actually, that's what those front panel fan controllers do, split one 12V molex up to half a dozen fans or even more.

Further, gaming oriented power supplies only have one single 12V rail, the multitude of cables and connectors is just for reaching every device within the case.