Hey Guys

I'm really new to the idea of modding. I'm wanting to create a campaign, with the normal rules as the standard grand campaigns (i.e world domination or whatever), however i want to eliminate some factions, and make some factions have more territory from the start. I.e Prussia would be MUCH larger, Poland would be a bit smaller, and the Italian States would be larger. I would also like to amend which factions are allies and which are already at war.

What tools would i need to do this, and is this even possible?

Cheers guys!!