So Moses went down to the people completes the third round trip up and down the mountain in this chapter. (A fourth round trip may be implied in verse 9. See the comments at 9b.) So is the usual conjunction waw.

And told them is literally “and said to them.” In Hebrew this is an incomplete sentence, for what Moses said to the people is missing. Most scholars believe that the rest of the sentence has either been lost or intentionally dropped in order to lead into chapter 20. Most translations cover this up as in Revised Standard Version and New Revised Standard Version, and New Jewish Publication Society’s Tanakh has “and spoke to them.” Moffatt, however, translates more literally in order to show an incomplete sentence: “So Moses went down and said to them…” The three dots, or ellipsis points, are in the translation. (Similar are Jerusalem Bible, New Jerusalem Bible, and Durham.) Good News Translation completes the sentence with what the context implies: “and told them what the LORD had said” (so also Contemporary English Version). Translators are urged to do this too.

Quoted with permission from Osborn, Noel D. and Hatton, Howard A. A Handbook on Exodus. (UBS Helps for Translators). New York: UBS, 1999. For this and other handbooks for translators see here .