yes
yes the iphone is easy to use!
Easy to use
No you both have to have an iphone 4 :)
Skinit makes it easy to customize your iPhone 4. Choose from thousands of unique styles of iPhone skins or upload a photo to design and create your own personalized iPhone 4 cases.
yes
No, there is although an iPhone case for the 4 that has a keyboard that plugs and you can use.
The iphone 4s desigh as same as iphone 4, so you needn't worry about that ,my girl friend's iphone 4s use my iphone 4 case (buy form 708buy.com) all the time, I prove the iphone 4 case is fit to 4s
it is not a easy question to answer. you should contact the factory which produce iPhone to check.
Yes. Easier than a Mac. Just as easy as an iPod Touch or iPhone.
touch screen lots of apps easy to use fun
No. It is not possible to use 2 apple ID's simultaneously on apple iPhone 4.
Yes I Use it every day it is my lock screen on my Mac and IPhone 4