These presets work for mobile and for desktop with the Lightroom app. For desktop you’re going to need an adobe account and subscription. For the mobile app you can just import them to your phone and use them directly. 

Yes you may and you should. Because every photo is different, you might need to tweak a little bit in order to avoid color aberrations or excess of exposure. 

Every preset pack comes with a detailed pdf guide that will take you through the easy process of installing these filters on your mobile/desktop

Yes, they do! Just follow the pdf guide during the installation process for your your device.