Jigga - if you hard solder, you will have to unsolder the ESC wires to the battery pack to charge/discharge and change packs. If you have plugs, like deans, you'll have to charge off a opposite deans connector like the one soldered on your ESC wires.
As far chargers, yes some chargers have dischargers built into them. Take the reedy quasar pro. It can charge, and it can discharge up to 20 amps. But the difference between the discharger built into a charger is that it discharges till the WHOLE pack hits certain voltage, ie 5.4V/6 cell pack. The Rayspeed Discharger and Novak tray discharges each INDIVIDUAL cell to .9V/cell. Two totally different type of discharger than one built into a charger. High competive racers have both.
Not necessary for starting out, it's better to skip some of the gagets to have some cash to race and learn how to drive an RC car.
As far as receivers, you should have bought one already since you got a Futaba S9550 servo? If not, the best of the line Futaba radio is the 3PK and you can buy just the transmitter and receiver since you need no servo's. Here's a link
http://www2.towerhobbies.com/cgi-bin...I=LXCML6**&P=7
If that's too much money, other affordable FM systems are available from Futaba, check out their website for a system that meets your needs.
John