Just to develop apple applications u will need a mac whatever u do, u can install a mac os into your computer, i don't recall very well what os should it be but anyway it's a mac one. You are going to nee and use mac os because you will have to use their tools, some of the tools might be free and findable for free over the internet, but some like Xcode are not free. You will need to buy it, so depend on what app you want to develop, you will find an appropriate tool for it. And i think that they do take money to allow developer to load their apps into the store but how much and the procedures, i don't know. With a alittle of google, you will be able to find many usefull informations about building apple applications and everything you will need.
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