Hi,
The fuel panel door only opens when the engines are off (makes sense not to refuel with the engines running, huh?) I hope that's the reason; stumbled over it myself.
I do have the loader utilities available, but not the takeoff calculator (but I have the fuel planner instead); if you can't find them elsewhere, I could upload it to my Google drive for you.
But tell me - does the multiplayer thingy work for you in FS9 / Win10? Mine doesn't, and I don't know why. Have just made a post for that, which is waiting for approval.
Boris