Questions about minternet

I have been a mint mobile customer for about 6 years, I switched from T-Mobile to mint, and like a lot of you, I never looked back. Last black Friday (2025) I took advantage of the sale and added two unlimited data plans for my daughters. I recently became aware of Minternet, I did not know that mint mobile offered this service in my area, and I'm definitely interested. My daughters are both out of the house, one of them is in college and the other one just graduated from USMC boot camp, just like me! (oorah!). I don't really use the home internet I currently have at home that much, except for streaming from Netflix as I am mostly out of the house because of work and my wife passed away a few years ago.

My questions;

1: Do I need to open up a new line to take advantage of the $30 a month current minternet offer? Or can I use an existing line to get the discount?

2: For those of you who already have Minternet, how are the speeds and latency?

I am located in the South of the beautiful state of Massachusetts, and speeds for the mobile phone lines we currently have are really good.

Any help is really appreciate it. Thank you.