Alerts to shoppers who are close to qualifying

I have a client that wants to have a clear alert on the site when the customer reaches the Free Shipping (based on $$) level. So something like a button changes color and words are shown “You Qualify for Free Shipping” on the site, as they shop…. AND

It would be great to have a calculator on the Cart page, where it knew they were only $4.12 from getting Free Shipping.

Would this be possible with your plugin (with some custom coding?).

Thank you so much!
S