If the airlines don't interline or sometimes just if you have separate tickets, yes you will need to collect your bags, which implies going through immigration (very quick and efficient at SIN) and customs, and then check in and recheck the bag after check in opens for your next flight. Until then you will not be able to access lounges except possibly through priority pass (SkyView or something in T1) as airline lounges at SIN are all departures lounges. Others have posted here that SIN has baggage storgage land side. You could explore the city instead of waiting land side or you might take a day room at the Crowne Plaza at SIN, also land side.

SIN is a wounderful transit airport, but you need to think carefully of the logistics of connections with LCCs here. Also, if you could fly SQ, they allow check in up to 48 hours before flights, so you would not potentially be stuck land side if you were departing on SQ.