Task 1: You could use Processing, and the Minim library.
http://code.compartmental.net/tools/minim/
Task 2: There are six analogue inputs on a Uno, and sixteen on a Mega. There are analogue multiplex shields (like Critical Velocity - MonsterMux 32 Channel Analog Multiplexer Shield Kit for Arduino P/N: MMUX32) available for the Uno to extend the number of inputs.