After recovering the debt and manpower from the mistakes I had done in part 4, I see how Portugal is in a worse situation than me. Its mainland got attacked and natives upraise in its colonial kingdom. Is there a better time to attack it than now? In addition, my technology almost caught up with the rest of Europe. So, just take the advantage and get as many colonies as possible. I will feel sorry if I don’t reconquer my lost territory.
AE really don’t matter for South America. First, there aren’t much nations in this huge land mass. Second, you are taking land from colonial nations, it just the colonial nation is going to be angry at you. Thirdly, the more you take, the quicker you are going to accept that culture, it means more tax and production and less unrest in the future!!
Lastly, make allies in Europe that has common rival, and I guess most of EU4 player know about this already.