Naval commanders and line of supply questions

[VonWulfen]

Hello all.
I came back to the game in the last few days and it has finally clicked. I am now playing the grand campaign and thoroughly enjoying the game now.
I am playing as the Royalists as my county was a firm Royalist region at the time.
There are a few things that I still need to understand better.
1 How do I create a clear line of supply?
2 I notice my fleets have no commander, and are suffering a penalty. How do I appoint a commander?
I did try dragging and dropping a 1 star general on the naval stack but he only became a passenger. I have yet to see a true naval commander in the game.
3 How does one create new naval units?
Many thanks