1st I have to say so far I love the game. Although the GUI needs some tweaking in alot of places, over all its a fine game.
Onto the suggestions:
I'd reccomend allowing people to stack anything. Really having 2 or 3 spare phaser cannons does not seem uncommon. Exspecially as some weapons work better on some mobs then others. So allow all like Items to be stacked in your inventory up to say 10.
As Stack is already avalible on some things, a split command to allow peeps to split thier stacks down for sale or trade or what not would be really helpful. In some games as an example if you use shift while moving a stack... it automatically asks how many to move. This would be very useful and probably not really hard to implement.
I know your not tring to waste our time needlessly or endlessly for no good reason LOL. However you did seem to ovrelook one key idea. Mass move of items from inventory to the bank or else where. Grabbing and clicking each thing independantly 1 at a time to move things to the bank with a full inventory takes a long time.
To fix this I would suggest "MOVE ALL" and "MOVE LINE" options, to and from both the bank and the inventory.
When it comes to the Fleet Bank, "MOVE ALL" and "MOVE LINE" should be an option set by the Fleet Leaders.
Can you say check box? I mean this is suppose to be 2300 something right? Hell even way back in 1990 Microscroft could make a check box for mass delete, I am sure Starfleet and the Klingons can too. LOL... Real simple options, each message should have a check box next to it. Clicking one at a time would mark those you want to delete, then click "Delete marked", additionally a "MARK ALL" should be tossed in.so you can mass delete the whole thing at once.