Let's say I installed it on my laptop Hackintosh.
There is no such need, it is possible to rent a VPS if the Internet is fast, you will be comfortable.
What do I need to start developing for Mac OS X/Iphone?
Quite Xcode, it is not necessary to download from the App Store, you need to register. You can download.
The iOS simulator will be there too.
do I have to pay for the Apple developer license (99$/year) to start learning programming and testing your code under this platform
No, just to elaborate, you don't need to pay for, and nowhere to register with a credit card, moreover, I think that your binaries for OS X will work the others. What to publish in the App Store, there is the option to shift it to the customer firm.
I wish you a successful learning development for Apple and too.