will they share the same SSID and will my devices switch between them automatically?
Theoretically, yes. This WiFi Roaming. Wireless clients will connect to access point with strongest signal if using same SSID but this not always guaranteed where signals overlap. Once connected to AP, clients will stay connected to AP until client decides to switch as you roam in area. For most part, this work, but sometimes not. Totally up to client wireless card and driver support whether it work “automatically” with AP.