what resources do you use for statistics on things like: how many people have iphones, how many ipads, android , etc and split by countries if possible. Do you know any site to offer such statistics?
It depends on what you want this information for, but I use google analytics, because it will show me what technology people that hit my website are using. For me, I don't care what everyone else is using, I care what my potential customers are using. Your target audience is not necessarily using the same as general averages, it could in fact vary dramatically.
Have you tried Gs.Statcounter?
They have stats about Mobile OS, Browsers, Destkop OS, etc., and it shows a graph for a time range (which you can specify!) and also you can see results country wise.
Though, it doesn't have absolute no. of users (which is anyways hard to get) and I'd not say that the results are completely accurate, but for me the results are good enough.