If I have a phone contact and I sync my contacts to my google account then will the contact see my email address in his contacts? If he has a google account too and I sync my contacts to my google account with his phone number then will google notice that we are in phone contact and therefore show my email contact to him in his contacts?

That is, does google reveal additional public information for connected people when it makes a connection between two people?
Yes, it does, especially if you or the other person uses Google Contacts app



Details for updating contacts and adding people are based on


Suggestions could come from a user’s Google profile, Maps, or a corporate directory when in an enterprise environment
Suggested contacts to add: You’ll now see suggestions to add contacts you frequently communicate with across Google’s products (Gmail for instance)


I have observed suggestions to add a Gmail address for a contact who corresponds with a different mail address with me.

Another source could be if you both linked Google + profiles