How should I adjust oven temperature/time to have two dishes ready at the same time?
25ºF isn't such a big difference, so I'd just split the temperature in the middle: 335-340F.

Instead of 60', aim at 50' and check for doneness by sticking a pin in the loaf. If it comes out clean, it's done.

I'd leave the casserole at 30' and then check. If it's done, it's done. If not, you can keep the oven going some time more.