Hey Papa, I'll almost guarantee that NO ONE has a remotely complete list of cartridges..."Cartridges of the World" is a pretty good source for information, but pricey. Personally, I recommend you simply buy Speer's Reloading Manual for Rifle and Handgun Volume 13. It has a good history for all the cartridges listed, and it has a pretty complete list of common cartridges in use in America, you'll be able to clear up some of your confusions. It has life sized drawings of each cartridge listed, and lets you calculate the energy of any respective cartridge, so you can determine which cartridge is more powerful than which.

Typically, the names simply use the caliber and have nothing to do with the cartridges' power level. Like "7mm" you mentioned has a 7mm diameter bullet, however, there are about 10-15 "7mm" rifle cartridges, 7x57mm, 7mm STW, 7mmRem Mag, 7mm WSM, 7mm SAUM, 7mm-08, 7-30waters and the list goes on. There are also several 9mm pistol rounds available, it's kind of like a first name, last name system. Kinda like "John Doe", "9mm Luger" defines the ONLY cartridge that is a 9mm Luger. There are other "John's" out there, like the 9mm Makarov, or 9mm B & B, they all use 9mm bullets, but don't have the same cartridge case.

Hold a 9mm Luger cartridge up beside a 7mm Rem Mag cartridge sometime at a gunshop, it'll start making sense.