In singapore, if you want to go out, then you can get visa at the airport, after you show your boarding pass and passport. Make sure you get the boarding pass to whereever you are going (I assume to Nepal) and you will get visa. The visa will be good for 30 days from the day of stamp.  If you want to stay in singapore, Reserve the hotel before you reach to singapore. It will be cheaper. It will be even cheaper, if you book via Singapore Airlines. They have some sort of package in their website.

I didnot book the hotel before hand, and I had to pay some bucks to be in good hotel.