EEC stands for "European Economic Community" afaik. This code was used on most of the early NES games released in Europe. Later when NES got so frickin huge they started to give each country/region their own code, like FRA for France, ESP for Spain, SCN for Scandinavia and so on.
The code in the middle, like NES-MW-FRA as you said is the code/serial for the game. The early game codes made more sence, like Soccer got SC and Volleyball got VB. But since its nearly 1000 NES games out there many of the codes doesnt make sense.
If you look at the back of a NES game with -FRA code you will see that the label on the back either says FAH or FAH-1. FAH stands for France and Holland. The FAH label only have french and dutch text, but the FAH-1 also have english. The reason why the manual got both french and dutch manual is most likely to save money. I assume its cheaper and easier to press one manual with 2 languages than 2 seperate manuals. Games that was released in Scandinaiva had swedish, danish and finish manual. So if you bought a game in Norway, Sweden, Danemark or Finland you would get the same manual
Some of the earlier games, like Trojan, uses oval "seal of quality". Its normal. I dont know why they changed it from oval to round tho. Trojan is one of the later of the earlier game (sounds wierd i know), therefor the game got EEC code, but the manual have another code. I dont think there excist a manual that says EEC. I've heard rumors about it, but never seen any proof of it.
As mentioned, earlier games started to use oval seal, so it doesnt mean the game is from USA just because it got oval seal. To find out if the game is from USA, you must look at the game and see if it says NES-XX-USA. Oval seal does not indicate that the game is from USA. Some of the earlier NES consoles did not have a region check so they are universal. If you try a USA game in your machine and it resets every secound it means you need to modify your NES (or that the game is dirty).
Nintendo made 2 PAL systems, PAL-A and PAL-B. PAL-A was used in UK, Italy and Australia, PAL-B was used in rest of Europe. Nintendo labeled the games and boxes with A and B so you can easily spot of the game is PAL-A or PAL-B. You cannot play PAL-A on a PAL-B console and vise versa. You need to modify your NES to do this, or have a universal NES as i talked about earlier.
Hope this info is to some help