Playing American Conquest, a narrative before the very first campaign (about Columbus' colonization) said that Portugal knew about the possible territories since 1470 and that there was some of the coast charted as early as 1452. How true is this?
I think this is still controversial at best. Here is a PDF summary of a symposium that covered the issues surrounding one possible voyage.
It is possible that the Portuguese had knowledge of the Americas before the Spanish. There were sailors going into the North Atlantic. And the Portuguese were aggressively probing down the coast of Africa. North Atlantic sailors may very well have come across Newfoundland. And it is possible that a Portuguese map existed as early as the 1470s. But the evidence is not conclusive.
Likewise it is possible that the Portuguese knew the Brazilian coast well before its official announcement of discovery. The winds and currents are both favorable to blowing ships to Brazil. Officially it was discovered in 1500. But an earlier date is possible. And a number of earlier dates and voyages have been suggested. It certainly isn't proof either way, but the 1494 Treaty of Tordesillas is interesting in that it protects Portugal's claims to precisely the stretch of the coastline they may have known about.