Ok, i could talk from my experience with Android:
Performance: This is not actually related with superpowers (not directly) but technologies used to generate an apk from a web app are not great when you have a slow device, that's a fact. if your users have android 5.1 they probably wont notice a bad performance since that webview works good with webgl, if they have android 5.0 or lower, you should use crosswalk to build the apk and you should know that devices with less than 1gb ram wont have the best experience (again, this is not related with superpowers itself its more related with technologies used for building the apk)
Ads and IAP: I used several cordova plugins for ads and they work as should, but to write the code you should be conscious of the situation: Superpowers won't have access to you cordova plugin code, so you have to write a code 'executable' without breaking code if it fails, and defined once the game have build from superpowers. example:
I normally use a variable with a check before use it:
declare let window;
let ads = window.adProvider;
if(ads != null) {
// Call your ad showing function (or whatever you need.)
}
Then build the game, and when making the code cordova-specific:
window.adProvider = YOUR_CORDOVA_PLUGIN_VARIABLE;
Now, if you havent work with cordova before. What i do is defining a variable when the event 'onDeviceReady' is called (which is before the superpowers game start to load) that way, when my game start 'window.adProvider' is already defined with some plugin variable (you should see the docs of the plugin you are using for better understanding of how to apply it here).
As a final thought this is a game i am developing where i use Superpowers, you could download it and see performance by yourself (is a work in progress, so if you have any bug, let me know).