1. i hope silk road can be integrated with the trading system, not as something you build. (I hope trade route value increase with distance and resource variety)

2. Olympics is cool, could be an event or recurring from wonders/culture legacy trait. not sure about the restriction and cost though

3.seem too complicated and exception, and add some issues, like if you attack it do you need to be in war with both players?

4.this thing could be nice if we have UN, and make it a law or project

5. Un yeah with dedicated mechanic if possible, and joined military manouevre could be cool as a diplomatic treaty to gain some xp

6.could be something from UN or similar to ancient one

7. yeah

Maybe some project to protect environment but could be tied with dedicated global arming mechanic which are probably not gonna be in vanilla

EDIT: some science big project like Hubble or CERN's Large Collider Hadron could be cool