Hi Winston,
I live in the Cayman Islands and our energy costs are about the same as yours. Perhaps even a bit higher as the utility company has a "fuel factor" which they increase as the cost of fuel for them goes up without having to go to any government agency for authorization.
I'm not sure what you mean by on-grid rebates not being economically feasible. Any money that you can get for power not being used is better than nothing. My local utility does not allow grid-tie so that is not an option for me, although I have purchased an inverter with grid-tie capability.
I've done quite a bit of research and I can't find any economic reasons for going off-grid. It depends on the pattern of your power usage, but storage capacity is always expensive, so I have quite literally taken the old adage "make hay while the sun shines" and applied it to my own situation. An example of this is my pool pump only runs during peak sun hours. Now on to some of your questions.
1. Economies of scale works in solar as it does in everything else, but separate systems mean that you don't have all of your eggs in one basket. It depends on the distance and arrangement between each of your chicken houses, but unless each of your chicken houses uses exactly the same amount of energy and at exactly the same time, then one large unit directing the energy to where it is needed will probably work best. Note that one large unit could actually be several smaller units from the same manufacture combined on the same power panel.
2. Hurricanes. We received a visit from Hurricane Gilbert in September 1988 shortly after it devastated Jamaica. There were a few recorded wind gusts of around 150mph and lots of downed utility poles, but most Caymanians now consider Hurricane Gilbert "cigarette smoking" weather. In September 2004 Hurricane Ivan battered us with 150mph sustained winds and gusting over 200mph for about 20 hours. I have designed a system that does not require any penetration of my roof, and in the event of a hurricane warning the panels come down and go into the house with me. I will try to get some pictures of my system up on this site in the next few months.
3. Panels in hot weather. Again I read as much as I could on this topic but could not find any independent comparisons. Based on everything that I read, the Sanyo 200 watt panels were my preference, but I was swayed by the economics of using the Evergreen 120 watt "B" modules and so far I am extremely pleased with them.
One site that I found very helpful during my research was the California Energy Commission. They test and authorize all solar equipment used in California and you might want to look at what ratings they give to solar panels compared to what the manufacture puts on them.
http://www.energy.ca.gov/