1. No.
2. Yes. You need to go to
Manage Content and Devices on your Amazon account on Amazon's website. Click the
Your Devices tab. De-register the broken device, or change it's email address. Then edit the email address that you want to use on the other Kindle to whatever it was on the previous Kindle.
Please note that you can change the email addresses on your Kindles to reflect whatever you want (obviously as long as no one else is already using that email address). For instance, my kindle's email addresses reflect my user name, and what Kindle version I have. So, I have one that is
pidgeon92DX@kindle.com for my Kindle DXG, another is
pidgeon92voyage@kindle.com for my Kindle Voyage. That makes it easy to remember which is which.
3. The Voyage is capable of displaying comics. Whether or not a specific comic is available in that format is another matter. If it is purchased from Amazon, it will be noted on the product page what devices can display the comic ebook.