dont worry too much mate. it is a nice country.
most of them usually take their holidays in Malaysia because it is cheaper, better food, more beautiful and natural holiday attraction. But do be very careful once u cross the border. be careful in all aspects because it is more chaotic on the Malaysian side.
there isnt much to do in Singapore, unless u really like to read (amazing libraries) and shop (good shopping malls). for first timer, I wold recommend going to the zoo. Gardens by the Bay is one of my favourite places to visit too. go to Sentosa Island for a quick getaway. clean beaches- dirty water though. the art museums r not too bad as well.
getting around is very easy as they have very efficient MRT system. just get urself an EZYlink card. and it is quite cheap to get around.
as for the people. on the train u may get a very depressed mood as everyone looks tired and unhappy. they just wanna play with their ipads and iphones to shut the world off.
most people there are kind of superficial, turn on your grindr and u will know. Singaporeans are experts in filing complains which is why the country is so organised and perfect in some sense, so be careful and be prepared with whom u r dealing with, most of them are extremely argumentative, and very materialistic too.
as for fitness, there is a great passion for running there.
have a look at this website, people post all sorts of true stories here. some are very gossipy stuff about their own people. and some can get very embarrassing. but this is how nosy people are...
they have a very helpful and attentive team in the singapore tourism centre, they can help u out a lot
PM me if u need any info, i'll help if i can.