Ok, I figured ourt where the Megamenu concfiguration went to in the template editor.
I found out that the whacky formatting the update brought was due to the fact that I had "Show Menu Title" enabled on all pages except the home page menu, which was simply a home icon before. Evidently mixing "no-show-title" and "Show title" makes alignment go whack. Now shoing title for Home, and at least the menue is aligned again, and the drop down shows up where it is supposed to. Bug.
Sadly, icons will not show. The down arrows are missing, with only a placeholder to show something's not right.
I've specified icons in the new megamenu manager for each of my main menu items, but nothing displays.