1. Up to you. If you softmod the 3.3E Wii and go USB then you'll not likely need to run backups anyway.
2. No 3.3 is a good starting point. You might be able to get bootmii/boot2 on your 2nd Wii, so you'll be protected from future full bricks.
3. No, start at 3.3 and update during the process. http://www.wiihacks.com/recommended-...d-any-wii.html
4. It's like asking why do fuel stations always stock Charcoal Briquettes and Firelighters. That's just the way it is.