Personally, I would not bother with upgrading to great speakers if I were not upgrading the amplification as well. To me it's a lot like polishing and waxing a car with scratches and rust. It's only going to be partially helpful. But you will have a following that will say otherwise.

Lpads are easy. Radio Shack usually (or used to) have them, and you can probably find them online cheaper. I used one on my jukebox that runs a pair of speakers on "A" channel and a pair on "B" channel, so that I could control the level between the pair inside the house and outside the house. Usually the Lpad will have inputs, outputs and left and right + and - pairs marked right on the terminals. There are also plenty of stereo forums with details, just google search them. If you get stuck, post a pic of your L-pad and what you wish to accomplish and the folks here can help you out.