@glssr - ask away, there are some real irrigation experts in the community (not me!).
Slope can come in handy even on a flat yard as Rachio will cycle soak - water, wait, water, etc. so that the ground has a chance to absorb the water and not let it run off - so don't just automatically change it to flat.
I think the two big things to get right are the soil type (there is a web survey site or the mason jar test) and the precipitation rate - you may want to do a catch cup test if you want to really, really fine tune it so that you know exactly what is being put down.