What is this amplifier doing, exactly?

@ Mike the only point I'd disagree with you on is the input resistor and that is to limit the base current to a safe value. 2K2 is 50 times the "bias'" resistors and as such will have little effect on their operation.. A .1 to 1uF cap (depending on the desired low frequency response) should work well with the 30 k or so input impedance presented at the base lead.

Bob