Maximums

[Sundjata Keita]

There is a stickied thread here with all the limits on (well the ones that we've worked out)

https://forums.totalwar.org/vb/showthread.php?t=42905

So in answer to your question 200 provinces is the max limit. 100 men is max for campaign for each faction. As for the roads I don't think anyone has really done too much experimenting, I assume there must be a default setting which makes them go from town to town but maybe try looking in map_trade_routes.tga