If I have an iPad with cellular, will I be able to text to all people like on phone and not just apple users?

Messages can only be used to talk with iPhones, iPods touch, iPads and Macs. If you want to talk with other people, you have to use Yahoo! Messenger or Skype, and they must have an account for one of them

Not without using a texting App from the App Store. The iPad has no other texting ability other than iMessage.

You can use the TextFree app https://itunes.apple.com/us/app/text-free-textfree-sms-real/id399355755?mt=8

 Cheers, Tom 😉