tech stealing is not in, and im not sure if it will be in until a later expansion the devs are planning an expansion to add espionage into the game at a later time.

as for tech trading once youve met a race and have universal translator you should have a   lets see if we can make a trade   option on diplomacy

after that any techs they have that you dont have will be listed on the right should be at the top before ships

any techs you have that they dont have will be listed on the left