Help with iOS app icons

I have some questions regarding how to save icon images for use in iOS apps.

I am designing the vector images in Illustrator, then copying them into Photoshop and saving for web/devices as .png files. Here is what I'm not clear on:

1. So, for an iOS app icon for example, Apple specifies one of the sizes as 114x114. When I create the new Photoshop document into which I will paste the vector file, do I need to enter 114x114 at 326ppi or just leave it at 72ppi? I have asked various developers and always get different answers.

2. Do I need to create my new Photoshop document into which I will paste the vector file larger than my largest bucket? Some sites I have read suggest this. So, if my largest bucket is 512x512 for itunes, do I need to start with a document that is bigger than that? If so, by what multiple? Double--so 1024x1024 in this case? Or can I just create the file at the exact size as the largest bucket (512x512).

3. I was told that I can simply save the largest file down to create the icons for the smaller buckets. So, if I have my image for the largest bucket as 512x512, I can then just change the image size to 114x114 and then save for web as my .png? Is this correct, or should I create individual vector and photoshop files for each bucket?

Thanks for any help.

AS for the dpi, it does not matter, its the pixel size that matters, not the resolution

I dont know about iOS icons but you can have one photoshop document at 512x512 and save versions using save for web and adjust any smaller sizes from within the save for web dialogue

As louishen as stated the dpi is not important, I use 72dpi for my images, and they work fine.

These links should help with your other questions.

https://developer.apple.com/library/ios/#qa/qa1686/_index.html#//apple_ref/doc/uid/DTS40009882

https://developer.apple.com/library/ios/#documentation/Xcode/Conceptual/ios_development_workflow/10-Configuring_Development_and_Distribution_Assets/identities_and_devices.html#//apple_ref/doc/uid/TP40007959-CH4-SW2

Hope this helps.

Regards Mark