Major shipping lanes and traderoutes on the map. Like convoy of ships moving from europe to asia when estabilish a sort trade agreement with particular nation there. Something like the Silk trade route would be great also.
This absolutely! Add the possibility to send pirates to rival trade routes and make it so that this hinders colony growth(this is what happened to Spain. The risk of pirates discouraged potential settlers from going to the New World). It would also be awesome if well defended trade routes encouraged settling of colonies but this might be OP.
I also think that Republican Governments should be revamped. To me currently they're more like a cheat: You can pick whatever kind of candidate(Admin, Diplo, or Mil) you want with no thought to who was popular. Now of course we can't add a voting system and even if we could I wouldn't support adding a feature that wouldn't even be used for most of the game. But there's another way to go about it. What if when the election event pops there is a candidate whose "popular" depicted by the "(Popular)" next to his name. This guy gives the bonus of a decreased National RR and increased base tax in your provinces for two years. Every time he's re-elected the bonuses are halved until they become penalties. This represents the idea that eventually people will tire of this guy. Now what would happen if you select an unpopular guy from the beginning? You get 40% chance for destabilization(-1 stab), 40% chance for increased national RR, 20% chance for a massive revolt, like on par with the US Civil War, like two 30k stacks coming into being would be a possibility. Now if the rebels win a special election event pops. In this special election the penalties for selecting the wrong candidate are doubled and the national RR increase is removed so now it's 50-50 of -2 stab or the mother of all rebellions takes place. If you select the popular candidate then you get a decreased stab cost and decreased national RR. So this is the game telling you to "just select the popular candidate, or watch as s*** hits the fan, like right quick!".
If this is put in place the Republican governments won't be cheats for long... *evil grin*