One) a physical keypad. There are two different Iris keypad models. One of them does work with smartthings and one of them does not. You will find detailed discussion of the one that does in the following thread:
Two) Exit and entry delay. Regrettably, the official security feature, smart home monitor, does not have exit and entry delays. It’s not clear why not. But it doesn’t.
However, you can work around that with core or some other options. Core is probably the easiest at this time. If you ask in the peer assistance thread, The people there will be able to tell you what’s possible.