Hey, João,
Regarding question 1), there's a preference you can use for iOS named 'target-device', which Cordova uses to map that exact setting.
As for question 2), I'm not entirely sure, but I believe that comes down to the submissions themselves: if you generate and submit an IPA targeted for 'universal', your submission will be usable and accessible for both iPhones and iPads. If you then generate and submit one for, say, 'tablet', then that upload will be pushed to iPads alone, keeping the iPhone version's last version as the latest.
Hope that clears it up!
Best regards,
Carlos Simões