1. The A/C is not working ( i drove with 36 Celsius out there!)
At this age there is probably a leak and it could get expensive to repair.
2. The gear clutch is heavy showing it needs renewal.
What is the latest with this. Often just bleeding the clutch can fix this.
3. The km menu is not working. No total km indication is showing either.
Note that the total distance travelled by the car is usually stored in both the engine ECU and an ECU on the display. If you change either component the display will show whichever of the two stored values is the highest.
4. Front driver window switch is not working.(Yes drove with no A/C or window!)
This is more likely to be the mechanism rusted and seized up in the door and nothing to do with the switch or electrical connections but check the electrics first.
5. The roof is hanging and needs renewal
6. One A/C switch is loose and cant change air vent direction
7. Color condition is bad but luckily i saw no rust.
8. central locking not working.
There is a wire under the dash that is an aerial to receive the signal these can become disconnected.
Finally most of your problems have lots of posts so please use the search function before asking for help. You usually find the answer already posted and faster than waiting for replies.
The search function is not easy to find but is here:-
Alfa Romeo Forum - Search Forums