A few questions about the BT shield, and Arduino

Can the BT shield be used to program an ArduinoMega?

And I’m wondering which Arduino I should use for this project:

I want to have an arduino send the raw data from a magstripe reader over serial to a computer. Then listen for either a “1” over serial and energize a node, then wait 30sec and energize node 2, or a 0 and energize a red LED.

Should I just stick with the ArduinoMega, or is there a lighter model that would work just fine? I ask because this is my first Arduino project.