Well in general I think most (all?) IP cameras are always streaming, in the sense that anytime a user is logged in to the camera, the stream is available to view in real time.
For example, if your camera is aimed at your front door, and you’ve setup a tablet running ActionTiles to login to the camera, you can see the front door anytime the tablet is unlocked and ActionTiles is loaded in your web browser.
Recording of that IP camera’s stream is a different function, which is not always-on, and could be triggered on and off in a number of ways. From what you’ve described, that’s not something you’re looking for.
So in my opinion, choosing the right camera isn’t the potentially tricky part; essentially any IP camera that can be set to stream in MJPEG will do. But how will you receive an alert that the camera has detected motion, and how will you set the tablet to unlock and turn on its screen when that alert is received? Also, how will the tablet be powered?