#7, well Singapore is a "fine" city.
#9, no need to bring my uncle into this.
You can get "therapeutic" gums at Singapore pharmacies.
Things like Orbit - which is touted to as good for teeth (presumably whitening) - and Nicorette, a nicotine gum aimed at helping smokers quit their addiction.
But Singaporeans need to submit names and ID numbers before buying. Assuming it's the same for tourists too.

Actually, I am quite curious why Nicorete which has "therapuetic" nicpotine doesn';t have the arse taxed out of it like normal cigeers which have normal nicotine.
What the hell's the difference? NONE.
and is it really in Nicorette's best interest to actually get you off the smokes? NO.
people who chew gum come across as a little Kansan for me.

Harry, they could insert some of that Nicorette into a rolled up banana leaf and smoke it..."electrical banana...gonna be a sudden craze." Oh wait, that song was about something else...also banned until recently in Singapore...but now legalized as a "therapeutic item"..."they call, me Mellow Yellow..."
But this is all a Chicle-ish Subject.

Someone mentioned that "importing" chewing-gum is against the law, and I have also read this on some website (which was perhaps outdated). If I bring chewing-gum in my suitcase, for my own use, is that O.K. or is that considered "importing" chewing-gum?
I'm talking about "therapeutical" chewing-gum like Orbit/Xylitol, which is indeed therapeutical (no, it's not whitening...), though I'm not going to get into that now... Anyway I am more or less addicted to it, and I'll only be staying a week in Singapore, so I can bring it in my luggage. Or is that against the law and will I end up in jail for attempting such a crime?????????
Please advise, as I have never been to jail in my life and I am desperately trying to avoid that...
Many thanks.
The govt will not put you in jail as they will have to feed you and give you free lodgings.
No, the practical way is to impose a fine so huge that you will only be left with bus fare to go over to Johor Baru.
When I was in Singapore last year, I still saw signs warning people of fines for chewing gum. Until they remove those signs I would not dare suggest you chew gum in Singapore. Just bring some for your personal use and ask the hotel desk if such law has been repealed.

it is okay - just chew and swallow. :)
just joking... but seriously, the best (and true) answer so far is #1 and the exception of food in the MRT as in #7.