Is the headphone remote/mic compatible with apple devices iPhone, iPad?

Yes, they are compatible with Apple devices.

Do these have a working mic to makes calls hands free and to use google Assistant hanfs free?

Yes, earbuds with microphone and volume control, which means hands free and convient for talking listen to music.

Do I need an adapter for my iPad 12.3.1?

You don't need adapter if your iPad has 3.5mm jack. You need an adapter if your ipad doesn't have 3.5mm jack.

Do all the remote controls work with an Android?

Yes, they do.