Order of events in hibernation
I think the order i,ii,iii should be correct, since the fall in temperature occurs after the heat loss exceeds production and will continue only till the temperature equals the ambient temperature. iv is the reason for i. Hence iv,i,ii,iii sounds pretty convincing to me. 

With i,iii,ii,iv , the main problem is that there can not be any appreciable fall in temperature ii after the temperature equals the environmental temperature iii. And iv seems more probably to be the reason for i rather than the reverse