I broke my jack holder piece too - just bought a new one and swapped it out. (Let me know if you want the part #)
Your spare tire could def. be the culprit for the noise from the back... in the 3 months that I've owned my '05 4.4i, I've chased down a number of little creaks and rattles, so I think it's just part of living with a taughtly-sprung SAV.
People on this forum are very knowledgable, so if you're having trouble tracking down a particular noise, describe it in detail and chances are someone will be able to help.
Good luck,