OP,
You are asking for options. That's just not gonna happen.
A player on a team going balls out economic should have to click a couple hundred times to transfer over that much to their aggressive teammates clicking out ships and orders and attacks. This way the number of user actions balance out.
Yes, it'd be nice if the game had more options and a little pop-up window where you could type in the number of credits, metal, crystal to transfer. Might as well wish for everything everyone's been asking for since 2008.