Thank you so much for the kind words!
To draft an Omen card, you need to have the right type and amount of Knowledge tokens. If the Awakening track is at levels 1-3, you only need to discard 1 of the 2 required Knowledge token types. However, once it reaches levels 4-5, you must discard both exact types of Knowledge tokens.
Regarding placing the Eucalyptus: you are absolutely correct. There are no ruling restrictions at all; you can place them anywhere you want on the map, as long as there is an open building slot available.