May i ask 2 questions at once?

I arrive SIN at Noon from SFO and layover until my 7pm to DEL. Having never been to SIN i want to go take a taxi in for a look around and lunch. anybody recommend best one stop area for first visitor? This is enough time right?

The following week I fly SQ SIN-PEN. Is the extra $30 worth ti for buisness class over Y on such a short flight?

many thanks.