Cocktails at Raffles = Rip Off. Go if you must, but you will feel distinctly lighter in the wallet area afterwards. A very nice place to spend the evening is over the road from Raffles; it's called Chijmes and has about 20 bars and restaurants in the grounds of an old convent school.
For electronics and cameras etc, Sim Lim square houses a lot of shops (400ish) in a small location. A word of advice, be very definite before you go about what you want: most places will have a load of models on display but will only carry stock of end of life models or whatever thay can buy in bulk. If you ask about a particular model they will "phone the warehouse" to check stock etc, and then try the hard sell on the model they have loads of while you wait. It's a PITA shopping there to be honest, i ended up getting the camcorder i wanted online after wasting half a day there.
www.visitsingapore.com has some good info on tax and customs etc, as well as a list of tips on buying electronics. Funan Mall is pretty good for IT stuff. Oh, Creative gear is very cheap in Singapore, it's made there!
Other stuff to do: Night cruise of the harbour is fun (leaves from Collier Quay, last about an hour and a half), Little India and Little China are well worth a visit, and wandering up and down Orchard Road shopping can easily kill a day.