may be less than ideal for water
sports in the second half of October. The water temperature may be in around 12-15C. Also this is the time of the year when the fall storms are frequent and can be nasty. 10B is not uncommon.
Fun things to do - it depends what fun you like.
Things to see - if you like medieval towns and museums? There is also a nice town called Sopot with very long wooden pier. The yacht marinas
are mostly in Gdynia - 1/2hr north by train.
Hotels - it depends on price
you would like to spend. From 2* to 5* associated with well known hotel
chains as well as independent. Proces are USD70 - 200. If you like you can stay in Sopot on the seaside ... 15min by train from Gdansk.
Eating - plenty of choice. Mostly East European cuisine but you will find also international as well as specialized. Fast food
same as in your town. Drink - in bars or pubs ... In the "Old Town" there are everywhere and some of them are very good.
Have a nice stay. If you would like to know more give me a shout.