yes a thousand or more years ago, heathenry was known to be held by people of Anglo-Saxon England, Scandinavia and Frisia(Friesland). there are also groups today that are reviving these old practises and call there religion by various asatru, the northern tradition, odinism, forn sed, Germanic pagan, reconstructionism or simply heathenry.
The plural of heathen is heathens.
In general, yes, although you would need to provide your own definition of "heathen" in this context. It's a fuzzy and poorly defined word. The person you think is a "heathen" because of your (and his) religious beliefs may well consider YOU the "heathen" by his standards. And probably you are BOTH "heathens" to some other third group.
Yes, heathen is the correct spelling.
The people from that town were heathen.
Heathen Beast was created in 2010.
Heathen Front was created in 1993.
Heathen Machine was created in 2002.
Heathen Harvest was created in 2003.
Heathen - The Rays - was created in 2002.
Heathen City was created in 2008.
The Last Heathen was created in 2004.
The Heathen Chinee was created in 1870.