Layover at Narita Airport

I am from Singapore.
I will have a 10 hour layover at Narita Airport at end of November. I will like to take the time to visit the temple at Narita.
As I have never leave the airport during transit, I would like to know if I need to obtain a pass to leave the airport and then re-enter for my departure.
Is the Rassurant Lounge at Narita airport still free for international passengers' usage?

If you are a Singaporean citizen, you can enter Japan visa-free so no problem, just enter like any other tourist would.

Naritasan shinsho-ji temple is not far from the airport and very famous temple.
http://www.naritasan.or.jp/english/index.html

You can go there by Keisei Electric Railway to Keisei-Narita station(8 mins), or, JR Narita line to Narita station(8 mins), then walk for 10 mins to the temple.
Alternatively, you can catch a taxi to the temple.

You can leave the airport. Just have to ensure the usual.
For international flights, you must be reach the airline counter for check in about 2 hours before. (Sometimes 1.5 hours)
You must also consider the immigration counter. (Luggage collection if changing airline group)

So you land and leave the plane and get to immigration (15-20 minutes depending on where the plane lands)
You go through immigration (5 to 30 minutes depending on queue)
You collect your luggage (5-20 minutes depending on usual factors)
You get take transport to Narita town (30 minutes)
Taking away the 2 hours before check in required, you have more than 6 hours for Narita town. Should be enough for 2 meals and some sightseeing.