Testing Jumpdesktop

I am trying to get a quick overview of Jumpdesktop and have a few questions:

- Do I have to install the desktop software on the target computer to access it via the internet?Isn't it enough to activate "Remote Administration" and "Screen Sharing" on the Mac?

- Can I have as many computers as I want on my list and connect to each one?

- What is Jump Desktop For Teams? Do I need this if I have multiple connections?

- Do I have to buy the Jump Desktop app separately once from the App Store and once the app for iOS and also once for Android?

- And is the iPhone and iPad app the same or do I have to buy them separately as well?

Thanks, Matts