dennis asks:Can it be possible that the word "Ghost" is a contraction of the phrase "God's-Host,"

It's just the Old English word they used to translate the Latin spiritus :

Middle English holi gost, holy spirit, from Old English halig gast, translation
of Latin spritus sanctus, halig, holy, See HOLY. + gast, spirit.

Host in the context of God's Host would more likely mean army as in the phrase God of hosts or in reference to the communion host: Middle English, from Latin hostia, sacrifice.

The God in God-spell is good. the word godspel is a translation of Greek euangelion, god, good, See GOOD. + spel, news.

All etymologies from the American Heritage Dictionary, on-line edition: http://www.bartleby.com/am/