On: every psalm and song in the daily prayers uses today’s English. Off: all of them use the older “thee and thou”. Until you choose, the Songs of Zechariah, Mary and Simeon use today’s English, as most churches sing them. The Lord’s Prayer and the prayers for the dying show the form most people learned.
A local assembly of believers where the gospel is preached and the sacraments administered. By the Augsburg Confession's definition, that is what makes a church a church.