1. No its not. Lending does not equal stealing.
If your car was stolen and used to commit a crime would/should you be held liable?
2. If you overlook the criminal part I guess you might be right, but thats not even certain.
Edit: I have noticed that much of what you have posted skips over intent and goes after the instrument used. (which could be many things other than a gun)
I have 5 different types of firearms. It is not my intent to shoot anyone, nor allow anyone to take my firearms and shoot anyone. Do I have complete and total control over the later? No, not totally. Should I be held responsible for something that is not totally in my control, even if that is my intent? Am I willing to use my firearm to protect my 2 daughters and wife? I wouldn't test my resolve in that case.
Your intent is irrelevant.
People don't intend to run red lights, but are held accountable when they do.
People don't intend to negligently maintain the parking lot in front of their store, but are held accountable when they do.
Just because you intend to use your five firearms for lawful things does not exclude the distinct possibility (and with five one could make a good argument that statistically its a probability) that one will be stolen from you and that gun might well be used to hurt or kill someone.
Bottom line: If you want to possess a firearm, knowing everything we know about how many are stolen every year and used in crimes, then you must accept the concomitant risk that the gun you buy will end up being used in that fashion.
So, if you choose to own anyway, then the incentive is really high for you to be as careful as you should be, anyway.
BTW, I think that this is something that you should be able to insure for as a rider on your homeowner's. If you buy a gun, you should get a disclosure form that tells you the potential liability risks and advises you to contact your insurer to see what coverages are available in the event your gun is stolen and traceably used such that a claim is made against you.
Your insurer could give you breaks for how you store the gun, what kind it is, where you live relative to crime, an alarm system. Those are things they do anyway but they could easily track that and establish your category of risk.