well... I just ran into another issue that may cause me to rethink my strategy: I just expanded to the 4th square of the frost island (I've alredy expanded to all squares in the main island) and I can't expand any further at the moment. I'm not sure if I need a higher level (25 at the moment - i have to get back to my real life soon anyway...) or if that is the current limit of the game, no matter which level you are at.
but now that my space is even more limited than before, I might rethink my strategy and buy more expensive habitats. or maybe a second grand farm and invest all my coins into food. that's too bad, I was expecting to be able to expand much further