7.2 volt battery is for motor. You should have gotten a speed controller as well. It has a circut in it that drops the battery voltage down to what the servos/receiver want. It has connectors for the battery, receiver and motor.
You don't NEED a switch with an electric, you jsut plug the battery in when you're ready to fly.
I'm not familiar with that model of receiver/servos. You will definetly want to check them on the bench before you install them in an airplane.

You don't mention what kind of battery it is, 7.2 volts sounds like Lithium Polymer. If that's case you'll a charger specifically for lipo batterys as well. Actually you might want to take those batteries down to your LHS and let them check them out... they're dangerous if damaged, and if they've been in a crash you want them looked at before too long.

I'm not overly familiar with Hitech stuff, but have had great results with their receivers and servos so far.

Andy