Wow, this would be a huge comment if I tried to tackle each of these topics! Also, it's only been about 2 months since I officially started e-mailing so take what I say with a grain of salt :)

I will say that It's been a valuable exercise to e-mail every unsubscriber and ask why they left.

The number one reason people leave is because they don't want to get an e-mail every day. We now offer a weekly recap email because of this feedback, and I've actually had people return to the list who had previously left.

Sending an e-mail to someone is a privilege. Especially a daily e-mail. In my opinion our time/attention is one of the most precious things we have.

I want the reader to be able to read and comprehend the opportunity in under 30 seconds and leave feeling like the e-mail had a positive impact on their day.

If you're looking for any advice in specific, get in touch, I'm always happy to help :)