Question about Mistplay

I've seen a lot of people (and advertisements about) talk about Mistplay, so I have a few questions:

If you have a spare Android device, how much can you realistically make over all from the app before it starts to "run dry" (I've seen people mentioning lower points over time)?

Do they want anything other than your email to sign up? I'm not comfortable letting them know my home address or phone number (I'm fine with sites like Swagbucks knowing, though).