please give pacifier to baby when the flight is taking off and landing, it relieves the pressure and helps to unblock the ears. you can feed her too if she is weaned off pacifier. just make sure she is sucking. Basically the flight is good as she would be sleeping...most of the time anyways. my god daughter flew to and fro SG & SHA since she was an infant till now (7yrs old) and basically the midnight flight is best when she was tinier.
not sure why you would want to bring her to the fish/seafood market but i dont think you cant bring her.
as for pollen, you really need to observe if she is allergic or not.