i was wondering all that i needed to start up and if the software would work on an older mac and where i could get it. PLEASE HELP
You need a machine with an intel processor that runs mac os x. To test on a device you need a device and acceptance to the $99 developer program. See developer.apple.com for details.
No, you just need to pay the $99 once and it covers submitting on the App Store and installing it on your device. You can "sign up" for free and get the SDK and Simulator all for free. You need to pay to get in on iTunes and your device. These tutorials were very helpful to me.