The ships do carry ground troops, but bear in mind that transport works on a "Weight" system -- in contrast to EU's system where Regiment numbers require the requisite number of transport ships with 1-for-1 capacity, instead -- in I:R the ships have a metric to factor out their weight capacity and your Army factors out a weight that varies whether it's Light Infantry vs Elephants (heavier, obviously). Basic strategy point - once you do get capability to raise Legions, figure out what that weight is for transport and that sets your "minimum fleet" build, with some spare ships as buffer. Moving on/off ships is similar to EU series movements, although I don't know if the penalties for direct offload into the face of an enemy army incurs penalties as it does in other PDX games.
I like the trade mechanics... I just want more smart automation (targeting what to focus).
Though apparently AI cheats and does not have to abide by naval ranges, or at least makes senseless moves. The number of times I see silly shenanigans like Rome (that is still locked in Italy) landing troops in Persia...
You can hire pirate ships the same way you can hire mercenary armies. That's probably what they did.
That is still a voyage from Italy to Persia without a single friendly port to resupply from in between. Even if it was feasible to land troops in Persia, they would accomplish nothing as this was not an imperial challenge war.
