Can somebody update me on Thor?

I haven’t read a Thor comic since I was a kid in the 60’s, but the JLA vs. Avengers discussion about Thor getting his ass kicked by Superman reminded me about him. A few questions:
Is he still the lame doctor who turns into Thor by hitting his cane against the ground?
Has it ever been clarified whether the doctor is Thor, becomes possessed by Thor, or hust gets the power of Thor?
Where is Thor when the doctor is just the doctor?
Does Thor still turn back into the handicapped guy if he loses his hammer for 60 seconds?