[SumAznGuy]

For CCM/RBK skates, D is the standard width. E is the "wide" width. When I wear CCM skates, after lacing them up tight, the D is a little tight around my foot. I found the "E" skates to be perfect.
BAuer/Nike uses the "EE" designation for their wide boots.

As for gear, I've never worn everything at the same time to test fit them. That being said, that is me so who knows.

What I recommend is go to Sport Chek/Sport Mart and try on the gear yourself. This way you don't feem obliged to buy it from them.

Starting with skates, the pricer skates will give you better ankle support especially if you are new or a power skater. But for your first pair of skates, I say go with whatever you can afford and feels good on your feet.
And since you have the skates on, try on some shin pads. Try the shin pads with the tongue slipped up under the shin pads, and try it with the tongue pulled down under the bottom of the shin pads. This will give you a good idea of what length shin pad you need. Since you are 5'7", assuming your legs are normal length, try some 15 inch shin pads to start.

When you go to try on pants, just wear them over some sweat pants or track pants and then walk around in them. See how well you can move around in them and how the padding is. Some of the pants do not offer a lot of padding around the crotch/inner thigh area but have great mobilty. Some pants have zero padding on the back of the leg, but that area is generally not important as you should not be blocking shots with that area. Tailbone/kidney area padding is important. With the pants on, stand up and see how far down the legs the pants go. Remember, if the pants are too short, you have no protection from the top of the shin pads to the bottom of the pants. If the pants are too long, that will interfer with your skating.