Yes, you can. If your iPhone is jailbraked, you can install iLog via installer. It helps you manage your calls/call duration/sms. you can get it here: www.ixtension.com If your iPhone is not...
I am pretty sure you can because it's called the iphone!
The messages app, open it, add a contact or type a phone number in the top part and in the bottom type your message. SEND
Yes, the Iphone supports Texting
Yes of course.
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