Save when (ei mē hotan). Matthew has “until” (heōs hou).
Should have risen (anastēi). Second aorist active subjunctive. More exactly, “should rise” (punctiliar aorist and futuristic, not with any idea of perfect tense). Luk 9:36 merely says that they told no man any of these things. It was a high and holy secret experience that the chosen three had had for their future good and for the good of all.