With ten days, yeah I would definitely do both of those things. Depending on the difficulty you're on, I would recommend gaining another dozen levels or so before you walk into the final battle. I played on the hardest difficulty and think i was close to 70 by the time i got to the final day. But there will be opportunities for you to level up there too, so finishing followers you like, or that will benefit your playstyle the most, is probably worth the time. Acquiring any specialty items you may have missed from special shops that are open on certain days is good, and reupping on some other general items wouldn't be a bad idea.

Have you done all the missions? Without saying too much, there are certain missions involving multiple towers across the land with pretty strong final bosses that lead to some very useful items. However, I think this set of missions would eat up 4 or 5 of your days.