My experiance, don't order or buy anything until you have a budget and a plan. I had to send so much stuff back after I found this website.
If you plan to develop into a reef someday then plan now on a FOWLR Fish only with liverock to start with. Start your research there. If you use local petstore, tell them you are going to start with a Fowler tank and if they don't know what you mean, don't accept any more of their advice.
If your not set on using the 55 I would jump to a 80 or 90 right away. It has a very small increase in footprint and uses most of the same equipment, Mainly the light which are going to be expensive as you upgrade. The canister is good for running carbon but thats about all. If you have good flow and plenty of Liverock then you only need a good skimmer and you have enough filtration.
Get advice here before you buy your big ticket items, skimmer, pumps, lights, any type of reactors or dosing systems and contollers. Don't be a beta tester, let others share their mistakes with you.
If you set it up right the first time you'll love this hobby. Fish won't die and algae won't make you curse.
Before I stop I want to tell you the secret weapon of fishkeeping. Keep this under your hat. REVERSE OSMOSIS, Shhhhhhhhhh...its a secret.
Mike