For a very helpful explanation on the use of the מן preposition, see BDB.
Other examples of the vav+perfect showing purpose include Gen. 35:5; 1 Sam 25:21; 1 Kings 2:31; 13:3.
For more on the “missing” dagesh lene, see Gesenius-Kautzsch §21.
About 1 min. into the video I introduce the “hovering dagesh.” I failed to mention that it represents a doubled consonant. Happy viewing!