Don't let good be the enemy of perfect here. Most systems wont be replaced in a year but even with tiny steps you can reach a milestone. It is extremely important to reduce dependence on other states for the own state to function, especially if it is led by a nazi orange.

Good!

I ran the back of the napkin math on this for my org (US local government). Not really possible unless you're just doing office work. Microsoft is so deeply ingrained in govtech that you can't even shrink your footprint. That's not even counting the political and cultural buy-in before you start the lift.

Very expensive but possible... in 20 to 50 years... If most of the EU cooperates... So... No.