Ah, another Super Cuber.
I started out with a Super Cub and am so glad it is the plane I chose. I, too, was following ozrcboy's and Leo's advice... as well as many other.
You asked for other things you might want to get from the hobby shop. Here are my recommendations based on lots of reading and some experience:
Pick up an extra prop or two. They're cheap.
When you get your extra battery, get the 8-cell, not the 7-cell like the one that ships with the plane. Don't go any higher than 8-cell, just ask the hobby guy for the 8-cell that fits that plane, they'll know what you need.
Get some packing tape. The clear stuff that you buy at the corner store for using with boxes. You can get the kind with little fiberglass strings in it for strength if you want. Doesn't look as good but is stronger. I just use the clear 3M packing tape.
Put a single layer of tape along the leading edge of the wing. This'll help if you crash or nick something. There are other small improvements you can make to beef up the plane before your first flight. Sometimes people crash and rip the landing wheels off, sometimes they break the fuselage (main body) off at the end of the plane (breaking off the tail).
The cub is a really strong plane.. I'm not saying its weak or prone to breakage... its just that beginning fliers can be tough on their planes. But anyway... those things I mentioned are easy to repair with the Super Cub - another reason to get it. But what some people do, is apply tape to those areas before their first flight to help strengthen just in case. Nothing too magical here, just take that clear tape and put one layer of tape on it. (not too much - keep weight down)
Here is the huge Super Cub thread on these forums. Its 175 pages of people posting all their experiences with the cub and different modifications they've made to their cubs.
http://www.rcuniverse.com/forum/m_4371835/tm.htm
Here is a board many of us are on as well. It is dedicated just to the Super Cub. There is a mods section that'll show how many of us have modded the landing gear, struts, electronics, etc. You can even put night lights or ailerons on it.
http://supercubclub.proboards78.com/index.cgi
Have Fun!