The 306 is rated for 70 gallons and will filter approximately 200 gallons per hour. With your 55 thats nearly 4 full water cycles every hour. Whether or not this is adequate depends heavily on your bioload. If you are planning on goldfish or some other 'dirty' fish, this may not be enough. If you have a very light bioload, then it should suffice. Again, it depends on what you are wanting to put into the tank.
you can never have enough filtration so buy the biggest you can afford. Buying something at or close to its rating (and that is a MAXIMUM rating) makes it work hard to keep the tank clean. I would prefer to get something rated higher so it isnt taxed as much. It's kind of like trucks. If you buy one that will pull 10,000 pounds and you pull 9,000 pounds with it, the truck will do the work but it is straining to do so. If you used a truck rated to pull 15,000 pounds, it will do the job and not strain as hard to get the job done. Going bigger will also give you some leeway if you decide to upgrade the tank. I have a 305 I use on my 37g tank and I love it.
The lighting is the same way. Are you planning on putting live plants in the tank? What kind? Different plants require different levels of light. If your answer is no, then 40w is adequate. If you want plants (and I wholeheartedly recommend you do because it looks so nice) then you will need a better lighting fixture.
The heater is probably fine but I would prefer 2 smaller heaters on opposite sides of the tank for 2 reasons. It keeps the temperature more even across the tank plus it gives you some redundancy in case one of them fails.
Air pumps are not necessary as long as you have some surface water movement as described in an earlier post. However, if you want one purely for aesthetics, I use a Tetra Whisper. It is very quiet as long as it doesnt touch anything else. Its amazing how much noise a power cord can make lying against one of these... lol Just keep it isolated and it's very quiet.