You can take bus "269B" from TST/Jordan to Tin Shui Wai. Then, you can transfer to Wetland Park by bus or Light Rail. Very convenient.
There is a Cafe de Coral restaurant in the park (in the entrance building). However, if you have walked out to the bird viewing area, it will take you some time for walking back to the restaurant. Hence, it is better you bring some snacks (small amount is enough) and a bottle of drinks with you.
Most of the places are outdoor with no cover. It is better to bring an umbrella if you don't want to get tanned.
I have seen quite some birds last month. As it is approaching winter, you should be able to see more birds in the coming two months.
At the entrance building (on the upper floor), I have the luck to meet with a volunteer worker who sets up a telescope and explain to people on bird watching. He is very helpful and try to share the interests of bird watching with people.