Tooltips in diplomacy/trade screen?

I'm a tad confused about trading tech to an AI.  First off I do no understand what the numbers mean next to the Tech Knowledge.  Second, it would be nice if there were tooltips about the selected tech so I know exactly what I'm giving and what I'm getting.  For example I am able to trade Civilization 3 and Warfare 1 and an AI has Warfare 6 available.  I have no idea what I would be giving or what I would be getting.  This is something that could use better explanation.