In a Chapter 7, a secured creditor is not required to file a proof of claim to preserve its status as a secured creditor. The lien will pass through the bankruptcy regardless of whether the secured creditor files a proof of claim - meaning that at the end of your bankruptcy, the secured creditor's recorded lien on the property will still be in place. If the secured creditor's claim is only partially secured, the creditor will need to file a proof of claim as to the unsecured portion.
Any interested party can file an objection to a proof of claim. So, as the debtor, you can file an objection to a proof of claim. In fact, if you do not object to the claim, you run the risk of the claim being deemed an allowed claim by virtue of no objection. Under your facts, the trustee or the other secured creditor could also object to a secured creditor's claim; but, leaving it up to the trustee or another creditor to timely and properly object is risky.
Evidence of all claims based on some sort of a writing (i.e. a contract, a lease, a mortgage, etc.) must be filed with the proof of claim. So yes, the contract you signed obligating you to pay and the assignment showing that the creditor is in fact the creditor, should have been filed with the proof of claim.
Yes, the automatic stay will remain in effect while your bankruptcy petition is still pending. Your bankruptcy will not close until objections to proofs of claim are resolved.
I'm uncertain if I can agree with the conclusion of attorney Kristina Michelle Reed, that regarding your converted case that, “Any interested party can file an objection to a proof of claim [… so] as the debtor, you can file an objection to a proof of claim…”
My understanding of the law, perhaps faulty in this particular circumstance, is that the conversion of your chapter 13 case to chapter 7 does not carry with it the proof of claim filed in your chapter 13; hence, if the creditor wishes to file a proof of claim in your chapter 7 they must do so anew. If a new proof of Claim is filed, you can as attorney Kristina Michelle Reed stated, file your objection.
Just call me a belt and suspenders kind of guy, but even if the proof of claim does not follow from the 13 into the 7 it is still out there. I do not see how it could hurt you to file an objection in the 7 and I can see that it could protect you. If the objection is not needed you will be notified, if it is necessary then you have protected your interests. The worst that could happen is that filing will cost you a bit of your time and you might have to file an objection twice if the first is deemed improper or premature and an objection becomes necessary later. As to the automatic stay, it will remain in effect as long as the property remains property of the bankruptcy estate or until a relief from stay is granted.
The ideas and opinions expressed in this comment are generalities only and not based upon a thorough analysis of your situation or the law that might apply to you. As such they are intended to be general guidance and not legal advice. Please feel free to contact us at 760-510-4900 if this is something you feel we can help you with.