About Singpore and chewing gums, it's all about them beeing fixed on keeping the city clean. (And it is!) Gums make nasty marks on the ground. But when I was there tourists could bring gums for their own use.
Beware of littering! On the front page of Singapore Times they wrote about three persons wanted for littering. One man had dropped some cardboard in a park and the Police expected him to have escaped to Malaysia.
Even though the city is largely more western than Bankok I found it very enjoying to visit. It has both a collonial heritage as well as beeing a stew of people of many cultures and religions. Get a Singapore Sling in the bar att Raffels Hotel, where it was invented.
Malaysia is a usually safe, muslim, country and very pleasant to visit. But check things like this before going:
http://travel.state.gov/travel/malaysia_announce.html