“Ten.” If you take the men in Joshua 17:2 (minus Hepher who was the father of Zelophehad), and the five daughters, there are ten children who inherited land.
“measured-areas.” The Hebrew refers to a piece of land that could be measured with a rope or cord. E. Fox (The Schocken Bible) uses “measured-areas,” which captures the meaning well.
“fell.” The exact way the lot was cast, or pulled from the breastplate of the High Priest, is not known, but the lot was Yahweh’s decision as if it “fell” from Him.
“beyond the Jordan.” That is, in this context Joshua is in the Promised Land, so “beyond the Jordan” is east of the Jordan River.