as far as what speakers fit, go to
http://www.crutchfield.com. dont know about any of the pioneer speakers, thats gonna have to be your preferance. but make sure you base your decision on the rms wattage, not the max. for installation, if you happen to buy your stuff from crutchfield, they will actually send you detailed directions for you to do the install yourself, as well as provide you with all the connections you need to make the install easy, usually for free if you spend like $150.
to hook up the sub, wire all the positives together, and all the negatives together. this will provide a 2 ohm load.
hope this helps