Drupal Site Backup Suggestions (Drupal 6, 7, and 8)

I will eventually start doing some further searching on this, and I may very well have found some info in the past in previous searches, but I thought I might as well just ask the folks here on Drupal.org for suggestinos.

I have a couple of sites currently running on Drupal 6, and one on Drupal 7 which I just totally took down when the major security announcement came out mentioning backdoors to sites. Since I built those sites, my time has been extremely limited, not that I had tons of time in the past to work on the sites.

I like the idea of Drupal in how it is structured, and as far as I can tell, I like the Drupal 8 overall design better (site/folder structure and such).

My question is really about 3 different possibilities, but at the same time, I can see where the answers could be actually wrapped up in one product or method or reference point.

So here are my scenarios that I'd like to consider:

1. Active Drupal 6 Sites - What are some of the best options/tools/methods for backing up site content in such a way that I could then create a new site in Drupal 8 once stable, not Beta, and more or less import the content? I'm not so much concerned with details like author and publish date, but more or less just the content that is typically visible to the end user audience. It'd be good to discuss back-end/maintenance type data if it's handled separately, but primarily just what the end user sees on a site.
2. For a Drupal 7 site - if I maintained a backup, I'm sure I have at least a couple that I didn't delete with the way I backup so much - I backup my backups. :) I'd like to know - are there any good ways to extract the content easily from say the database backups and/or site backups. I suppose it would have to be MySQL queries assuming that is the database used, but are there any good tools/options out there along those lines?
3. For a Drupal 8 Beta site, What good methods are there to back up the content between releases, then export, and re-import into new sites? Would the Backup and Migrate Module(s) be all that I would need? Would something like that break between Drupal minor version upgrades/re-installs? The reason I ask is that the couple times I've attempted a minor version update on a test Drupal 8 site, every attempt has failed. I've ended up just scrapping what I did, and starting over. It's not the end of the world at this point, but it s disheartening, since I don't have all the time in the world to repeat, repeat, repeat, and repeat my efforts at testing a new site build.

My question is more so for front-end developers, I suppose, as I do not have time with my non-drupal, non-web deisgn, responsibilities to get much farther into it. I do hope one day to look into scripting methods such as using Drush (which I did look at, prior to Drupal 7), and get more familiar with those. That seems to really be the way to go in order to cut down on some of the monotony for some tasks.

Thanks in advance for any thoughts or suggestions.