Of course, it should come with all needed. I was referring to the diagrams you showed, seemed too complicated. The only UI additions should be numbers (maybe as a bar, like capture points right now) and icons indicating what is present and what is absent. A very fast example for a Triērēs (after doing everything I realise it says Tetrērēs, but the game represents them quite wrongly as Triērēs anyway, just with sails set) to show some ideas: I've added, on the right of the sword and shield, very preliminary icons for the trierarch, helmsman (low quality ancient rudder), rowing master, and bow officer, with the latter having died in some recent engagement. On top of them, capture points are not used any more, but the 170 rowers and 24 deck troops. On top of that, icons for the shipwright and purser specialists, and the piper should be there also for a total crew of 201 (and there are 3 extra embarked units). I'm just testing possibilities, not sure what the standard should be, maybe all could be on that higher placement (around 9 icons seem to fit there), or maybe on the lower one, but with smaller icons. Maybe all specialists could be included for each ship type, and only the absent ones shown, with a red cross. The simpler the better I'd say.

This was the most eastern archer I found. He's from Cyprus.    

I thought from the start that when you train the ship, it should already come with a basic crew.   Let's think of something simple: a modest exploration ship with a couple of warriors and a basic naval commander.

Currently there is only one artificial limitation - silhouettes system. It stores occluders as 16-bits indices to save memory. So we can have at most 65k units with silhouettes enabled. Without it's limited only by hardware as @Stan` said. But the silhouettes system is very easy to improve to not have that limitation.

By searching for Julius Terentius you can find images of artistic recreations. By the third century, this seemed to be the standard.