Good questions: #1 a) most people don't have multiple packages coming in. If they do, just remind them both are due today, simple. Only send SMS alerts between

Good questions: #1 a) most people don't have multiple packages coming in. If they do, just remind them both are due today, simple. Only send SMS alerts between 9am-9pm so you don't wake them up. You can get their time zone info from their address. #1 b) just use email alerts if they don't want SMS alerts. #1 c) when customers checkout they have to enter their email and phone anyway just a checkbox next to both with the option of (alert me the day before my package is going to arrive). They can choose 1 or both. The rest are just preferences, I added an edit on my blog to better explain the whole guest checkout is important thing.