That's for own ships? What about enemy ships? Used to be you could see the (arrow) stats and know what's up, but that has been changed.

Antesignani as stated in this post. Obviously, until we have more evidence, we must be cautious.

You are welcome to post where you think is best.  Codewise, a good improvement @ffm2 would be packing your mod as an extension of localratings. In practice, include (only) your additions in a mod, and add localratings as a dependency. It will simplify maintaining and distributing the code. It will also ensure compatibility with the base mod across versions. Up to you - but I think your work will benefit! 

It would look good with some Iberian pattern.

Hi and welcome to the forum! Unfortunately, the  only way I am aware is to actually select the ship and see the garrisoned number of people. There has been multiple suggestions to modify that so it will be addressed.