A:AnswerIt comes with the charging cable but not the adapter (the block that you plug into the wall). That you need to purchase separately unless you already have one that you can use.
A:AnswerYes, I bought bands off amazon for my apple watch series 3 and I switched them to my series 8. There might be some edges visible depending on the band, but they work great for me
A:AnswerIt does not alert you automatically, you have to click on the app in order for the ECG to begin. It does show the results and it shows the ECG that you can send to your doctor.