Quote: "So you can set up an IOS account etc on windows paying your £99 and then just build the APP on a MAC in the same way as building a pack for Android?"
Yes, pretty much. So the only thing you actually need the Mac for, is exporting the .ipa and submitting it to Apple via Application Loader.
One additional step you will need to take when you
first get your Mac access, is to create a Signing Certificate, which you then upload to your Developer Account - this only takes a couple minutes. Once the 'Signing Certificate' has been created and uploaded to your Dev Portal you will be issued a 'Distribution Certificate' which you will need to download on the Mac and add to your Key Chain (again, this only needs to be done once (or until it expires)).
Also, I believe its $99, not £99, so a little cheaper
Quote: "Do you need a key like Android?"
Apple have what are called 'Provisioning Profiles' which are specific to each app (much like Android Key Stores) these can be created and managed from the Dev Portal via a Web Browser (I do this in Windows).
Once you have the 'Provisioning Profile', you download it to your Mac and provide it when exporting the ipa from the IDE.
Quote: "If you know someone who has a MAC could you just build the APP on their amchine and then save it to a USB stick then upload it from windows?"
No. The application (.ipa) must be submitted via a Mac using either xCode or Application Loader.
Quote: "Do you have to pay the £99 every year or can you release as many APP's as you want in a year and they still sell if you don't renew?"
Yes, the $99 has to be paid yearly. If your Dev Membership expires, all of your apps will be removed from the Store.
This may sound a bit complex, but honestly, its pretty straight forward! Like I say, it only takes me a few minutes to submit my app. The worst part about Apple is that they require a ridiculous amount of sreenshots of different resolutions, but as this can all be done on Windows, you can get all this done before even accessing the Mac...
Hope this helps...
Using AppGameKit V2 Tier 1