The bomber vs. ship thing initially annoyed me. But, I think it is OK for play balance.
The AI has a tendency to have overwhelming numbers of units. If you tried to approach his shores with a landing fleet you would be decimated before you reached the shore.
For fleet vs. fleet action, aircraft carriers with bombers become critical for success and overcoming attrition.
With the 1.7 patch, cruise missile can now sink ships when targeting them with 1 hit point left.
I'd love to be able to carry a few cruise missiles on a sub.
IRONIKINIT -- to answer your trading question... pull up the civ and look under "current" (or whatever it is called) at the bottom right of the trade dialogue. This will show you the trades you have going with that civ. It will show up in blue if you have the ability to renegotiate it. NOTE: once you click on it... you've cancelled it and set it up for immediate renegotiation. Becareful if you have a great deal going.