I apologize for the delay in response to your question. Yes, there are parts to do everything you are asking.
To do the steering wheels, get the Metra ASWC adapter. also found here http://www.amazon.com/Metra-ASWC-Universal-Steering-Interface/dp/B0039H2W66/ref=sr_1_1?ie=UTF8&qid=1320633877&sr=8-1
To integrate subwoofer, you need this harness. Metra part number 70-5521 also found here http://www.amazon.com/Metra-70-5521-Radio-Wiring-Harness/dp/B000K50GTA/ref=sr_1_2?ie=UTF8&qid=1320633953&sr=8-2
Please don't splice wires, as this always makes for a headache for somebody in the future.
However, do take note of something I've found on some of the fords. The blue/white amplifier turn on lead must be connected to the blue/white wires on the amp plug for the subs. Sometimes you will get a considerable POP sound when the amp turns on. If you put a 300 ohm resistor inline with the blue/white wires if this happens, it should eliminate this pop.