well I let the sims do by themselves 24/24 7/7 and everything goes right since my last post, crops come and go but seem to follow a cycle as you mentioned. Now I've all level 2 and Harvesting and Building in level 3 thus no food problem anymore thanks to fishing.
The game is even a bit "long" now that I need to wait on to reach a high enough number of tech points to buy some new skills. Anyway life seems sweet on the island apart from a tornado which left my beach dirty :-) ... but the sims took care of it and everything back to normal.
To answer you question yes I started playing with version 1.0 and didn't know you could upgrade to version 1.1. Anyway as I understood savegames are not compatible I prefer to finish my initial game.
Thank for your help