Welcome to turtle ownership!
If you haven't already, be sure to read through the main site (
www.redearslider.com). There's tons of information there!
The 30 gallon is a great size starter tank, and should last your little RES about a year. The amount of water in there looks just about right for a hatchling. RES are aquatic, so they like lots of water. You can raise the water level as he grows, and when you get a more permanent basking area.
When you get out to get supplies for your new little guy, beware of "basking bulbs". You want to make sure the bulb you get actually emits UVB light. "Full Spectrum" bulbs don't emit much, if any UVB light. A UVB light will say "X.0" or "X%" UVB. Most people recommend 5% (or 5.0). There are tube lights that fit in aquarium hoods, or there are CFLs that fit in a regular socket. If you go for a CFL, it's recommended you get a 26watt, not 13 watt. You can use a regular incandescent household bulb for heat.
You'll also probably want a heater for the tank. Hatchlings are especially vulnerable to temperature fluctuations, so the water heater will keep the water temp stable.
You'll need a thermometer too. For hatchlings, you'll want to keep the water temp at about 78*F.
A filter is also a must. You'll want a filter that is rated for at least 3x the volume of your tank (so for a 30 gallon tank, you'll want something rated at least 90 gph).
The little basking area that you have will be OK for temporary, but he'll quickly outgrow it. Many people use the Zoo Med floating docks, or these type of acrylic ramps:
http://www.drsfostersmith.com/product/p ... catid=8809
You can also build your own (there are lots of idea in the indoor habitat forum). In general, it's better if you can maximize swimming room, rather than take swimming room up with something like stacked rocks.
Pyramiding is when each individual scute is raised, not the whole shell. Hatchlings often have a shell that is raised towards the center (like yours), and it's absolutely nothing to worry about. As he grows, his shell will fill in and become more rounded.