Upgrading Ships Time and Repair

Yes, I've posted about this in another thread. The current system lends itself to cheesy exploits far too easily at the moment. Basically, i think the upgrade sytem needs reforming. My idea was as follows:

Each turn, the player can work on a number of upgrades limited by his logistics ability (so one fleet's worth, basically). Ships in orbit around planets with shipyards or military starbases take 1 turn to upgrade; ships in a sector with a player planet take 2 turns; ships in a sector with no friendly planet take 3 turns with a +25% upgrade cost penalty; ships in a sector with enemy planets take +1 turn and a +25% upgrade cost penalty. Ships cannot move without cancelling the upgrade and writing off the upgrade cost, but ships can move/fight normally until it is their turn to start being upgraded, at which point they'll be parked, so you can issue a general upgrade order, but still be able to order active ships to return to base (see below). I think it is reasonable that ships are completely repaired after being upgraded. but I guess there's nothing wrong with adding to the upgrade cost... say 10BC per hitpoint repaired. It's a minor issue IMO.

The upgrade cost to be deducted when work starts on a ship, with players no longer able to go past -500BC of debt in order to pay for upgrades (this stops the cheesy tactic of being able to suddenly buy a huge superfleet), with ships entering the upgrade queue in ascending order of upgrade time (so ships that take 1 turn are started first, then ships that will take 2 turns, etc), and then in ascending order of hull size (so Tiny ships first, then Small ships, etc.).

So this system still allows the convenience of issuing a general "upgrade all" order, but without the exploit of suddenly creating an uber-fleet inside another player's border regardless of expense.

Yes, upgrading has a lot of cheese at the moment. E.g. it is cheaper to buy an empty hull and then "upgrade" it with weapons than to buy the full ship directly. And last time I checked, it was ridiculously cheap to change from mass attack to beam attack, for example.
The most important things would be to change the way the upgrade costs are calculated and not to heal ships that are upgraded. I also agree that upgrading goes to fast usually, it could be a good idea to tie it to the logistics level.