>>216633169
Thing is, during this period of time Bohemia and Poland were doing good compared to other countries.
Historically speaking, Prussia could only defeat the Commonwealth because it was internally divided and had to deal with the Russians to the East, Poland at the beginning of the game is a stable realm with a relatively powerful and centralized crown, and it was one of the countries that dealt the best with the bubonic plague.
Similarly, Bohemia at the start of the game has a good amount of population, no internal division and the Bohemian king was the Holy Roman Emperor.
The real problem with Bohemia is that the emperor snags random territory in the HRE and that the Hussites aren't too hard to deal with so Austria (or alternatively it could be Bavaria or another rising German power) don't get the Emperorship.
>>216633407
When I got tier two roads as France and tried to used them to lower control they barely impacted it so I don't think they matter that much.
Also, besides roads you can build bridges, they can be built only in locations with rivers but they also lower distance cost and increase army speed.