As for me, I'm keeping one ship of each class,that way I can train additional
crewmen as you need more when you advance in the game

Thanks for the replies guys. So should I sell my frigate 01? It isn't really all that useful. Also, for my second question, what I meant was do you get a new crew for each ship? Or do you just pull people off your other ships to man your better ships. I guess it was sort of answered in the first reply but I wanted to know what you guys were doing.

Sell ships that you aren't going to need. You will not need to keep more than 1 DD, and the cash you lose from selling a DD is minor. It's nice to keep a ship from each class (DD, CL, CA, etc.)

I'd say keep all your ships. I havn't sold a single ship yet.

To your second question: Yes. Your crew levels up, and get better and better ships and equipment. As long as the ship/equipment is of the same nation, you can use your force on any of that nation's ships (Provided they are of the appropriate level, of course).

To the first question: Sell only if you are deeply in need of cash, as there is a penalty for selling equipment, FCS, and Engines.

Thank you for asking in a coherent and non-swearing manner, too!