Aside from the well-touristed fortifications in Viscri and Biertan, churches in smaller villages can have unreliable opening hours. You may have to rely on calling a phone number posted outside the church, to ask a caretaker to let you in (if they answer, that is). Ask locally if you have your heart set on a particular church, and allow plenty of time.
Traditional guesthouses are sprouting up in villages around this region, with some especially rustic options in Viscri, Alma Vii and Mălâncrav; some can be booked via Experience Transylvania. Biertan has a good range of pensions.
Unless you plan to rely on roadside honey, peach and mushroom stalls, Biertan is best for restaurants, while Mediaş has some mediocre ones and supermarkets too. Restaurants exist, usually attached to guesthouses, but opening times can ebb and flow with tourist traffic, and small, family-run establishments aren't always able to open the kitchen for unexpected guests.