Yes, the four woofers are wired in parallel. On older woofers, the positive terminal has a red ink line next to it - and it's very subtle. Newer woofers have a "+" and "-" imprinted on the terminals.
The positive terminal on the cross-over is the point where the capacitor and inductor are connected together. The other side of the inductor should go to the positive input, and the other side of the capacitor should go to ground.
I need to correct my post here after rebuilding my right Plat. The positive (red) wire from the inductor in the woofer crossover actually goes to the negative terminal on the woofers. Thus, the woofers are inverted in polarity. Also, read the service manuals, they also specify the polarity for the woofers, which is different depending on the series.