Looking for info/advice on leveling up a medic for my CV.

I've heard the following:
potential is the best stat I need.
If placed with a seamen, they both work.
For IJN, I need to use the KM medic. (Can I & should I "level-on-time," and use my IJN
ships, or do I need to make a KM ship line?)

THANKS!

good info here: http://www.trainworld.us/NF2/sailor_flowchart/description/Medic.html
(so don't tell me to look at it. : )