A: Us women don't trust men generally.I personally would be jealous all the time if a guy I was interested in or started dating was still talking to his ex even if it's on a friendship level.
A: - do that whole lint picking thing - do the playing with your hair - subtly licking your lips - do the whole glance at him look away and then look back with a shy smile
But honestly you should just tell him or ask him out for coffee."hinting" just wastes time