Start with How to get started (there is no step-by-step tutorial) (some of which resources you have already encountered). This will give you a good background on how OH over all works. You need to know and understand the parts of OH and how they work together to be successful.
I do not see a binding for either of these. I suspect they are using the HTTP binding. Usually they will say in the thread or it is apparent from the way the Item is defined.
No. An MQTT broker needs to be installed and configured. The MQTT binding needs to be installed and configured. And in all likelihood you will need to manually configure Things for these devices unless they happen to follow one of the two supported standards that allow for automatic discovery (Homie and HA) which is unlikely.
All the sources you identified should still be current. Especially the OH docs themselves.