1. If you mean you bought iPhone apps inside iTunes, you can transfer them with iTunes or redownload them in the (iOS) App Store directly to your iPhone.
2. If you mean apps that run on your Mac, you cannot transfer them to your iPhone; they would not work there. Mac apps are not iOS apps. (In some cases, one company makes a Mac app and an iOS app with the same name that do the same things and/or work together, but they are not the same sets of bits.)
I have this question too. However, I haven't purchased an iPhone yet.There is a new birding app which I wouldlove to be able to to take out into the field on an iPhone. I am wondering if I can buy one without subscibing to any phone company or internet connection. Then purchase an app from iTunes which is suitable to run on an iphone and transfer it from my MacBook via a cable of some kind?
Mac Applications do not run on iOS: iPhones, iPads, or iPod touch. And the reverse is also true.
If the manufacturer wants to, they can port their Application to the other platform and offer it for sale there as well.
To download IOS Applications directly to your iOS device, connect it to a WiFi Access Point. You do not need to have the version with a Phone plan. An iPad (WiFi only) will do what you desire directly, no phone plan. iPad Mini might be good for field work.
Thank you that is helpful. I am still wondering whether an iPhone also has a WiFi facility. In case I later decided to make the phone operational and use it to tether my MacBook to the internet. At present I am using a portable wireless attachment. On going telecommunications costs are a big consideration for me in Australia.