Do I need WiFi & Cellular on a personal use iPad?

That is up to you. If you get a wi-fi only device, you will need to be connected to a wi-fi network to use it. If you get a wi-fi and cellular, to be able to use cellular data, you will need to activate that with your cellular provider, and there will be a monthly fee for cellular service, but it will allow you to use outside of wi-fi.

Carefully consider selecting a WiFi Only model of any iPad. Only the WiFi+Cellular models include GPS functionality - the WiFi Only models do not. 

We frequently see complaints and dissatisfaction from users who subsequently learn of this limitation after purchase; not only does this fundamental difference affect the reliability and accuracy of Location Services, it can also influence use of some Apps - such as mapping.

Selecting a WiFi+Cellular model of iPad doesn’t lock you in to using Cellular connectivity, but in addition to providing GPS functions, does provide the flexibility of using Cellular connectivity if your needs require this functionality.