iPad cellular and WiFi

You can't. A cellular iPad is not a cell phone. It doesn't have a cellular radio like a cell phone. And without a companion iPhone it cannot send or receive SMS/MMS text messages, nor send or receive phone calls. If these are features you want to be able to use on iPad, you need to have an iPhone.

If you are within the standard 14 day no questions asked return window, take it back and get the iPhone instead.

You're welcome. When finances are in your favor, getting an iPhone will make it all work and work really well.

You can't really. It's not designed to make calls without being on the same network as an iPhone with the same Apple ID. The cellular capability is really only for cellular access to the internet.