Brandon,
Welcome to this crazy hobby!
I will give you my .02 and I'm sure the others will chime in and give theirs, especially Carmie, who I believe has a 54 corner.
1. The
T5 will be fine for keeping the tank
FOWLR (fish only with
live rock). Honestly, while you are learning over the next couple months , this will be fine. You can add to it later if you decide you want more light loving critters.
2. I'm not familiar with the Sea Life
sump. Most of us are the type that
DIY our stuff, but if that is not your thing, it may be fine. What return pump are they suggesting for it??
3.
Skimmer...you have a ton of choices and its a decision thats best made once you have the tank running and can see ow much space you have under the stand.
4.
SSB vs.
DSB is still very much debated. I personally dont care for the look of a
DSB in the display, but thats just me. Which ever way you go, I would skip the bagged live sand and instead seed your sand bed with a cup of sand from another trusted tank (or tanks).