So, I want a new character but I want to mod the whole game. I want to have a difference experience of the game.
More quests, houses, weapons, clothes, maybe races, everything! Maybe a whole new country, I don't care!
Do you guys know any good mods that can help me?

I would suggest...

Texture mods (No such thing as TOO pretty!)

Some new animal packs (there are plenty of these)

Hearthfire (or one of the mods which does the same thing)

I think (but I'm not sure) there are some mods that expand the map, into areas like Morrowind and Cyrodiil. But I'm not 100%