Yes. Once an addict, always an addict. ('Irreversible changes to a brain' are quite common. You remember having smoked, for example...) More importantly, this was something emphasized before, and so it is irrelevant to bring it up as a supposed counterexample.
I fail to understand how nicotine on its own would satisfy an addictive craving created by a different chemical or combination of chemicals, if it isn't addictive itself.
I'm afraid I don't understand what you mean about a previously emphasized counterexample either. Could you elaborate?
It's pretty hard to get addicted to nicotine patches, if you never smoked.
I don't see this as an argument that nicotine is not addictive - just that different routes of administration are more or less addictive, similar to IV vs. oral opiate use.