If I don't have a iphone yet could I sigh up with icloud and buy my apps?

Yes currently I don't have my phone yet, but I'm getting it soon could I buy my apps and when I get my phone then download them on it. If the answer is yes please explain how to do it

No, how do you expect to select and download? Just in the thin air?

Follow this of your own free will, I tested on my end but I own an iPhone. So I can't 100% say that this will work for you.

If you have iTunes download on your PC/Mac go to the iTunes store. Then choose App Store along the top, locate the app and then you can purchase it.

I just tested and the app was available to download and showed as purchased and clouded.

Just make sure that you are signed into the account that you are 100% sure you will be using on your iPhone once you get it. The apps are only usable if the sign-in is the same.

Yup.

Just use iTunes, make the account, & download what apps you want.