How to archive and backup our questions to our own PC just in case? In order to be cautious for possible future closing of the site....
1$\begingroup$ The short answer is that a full copy of all the stackexchange sites is available through the StackExchange Data Dump. You could download one, if you want. $\endgroup$– davidlowryduda ModOct 16, 2016 at 4:07
$\begingroup$ So you mean there's no way to backup our own posts and questions? $\endgroup$– Hamid Reza EbrahimiOct 16, 2016 at 4:13
2$\begingroup$ How do I know I won't lose all my work in math.SE?, Backup, save, download all questions and answers for individual users, Extracting all my answers (and the questions) $\endgroup$– Martin SleziakOct 16, 2016 at 6:29
$\begingroup$ Is it possible to extract our work from a downloaded full copy of stack exchange site??!! $\endgroup$– Hamid Reza EbrahimiOct 16, 2016 at 6:38
$\begingroup$ For me, my current answer is "hope and pray this site never closes!" It's a good question...('cuz sometimes despite all our hopes, bad things happen...) $\endgroup$– amWhyOct 16, 2016 at 19:35
At a low level of activity I would manually "Save as..." each Webpage containing your posts (using your favorite browser), producing a complete copy of HTML and images locally on your own PC. (I can also recommend some kind of backup strategy for your PC, of course.) Such copying is naturally allowed by the terms of Creative Commons by-sa 3.0 with attribution required.
If there were a larger body of work to save, scaling up with some sort of browser automation will be attractive. This would involve a substantial programming aspect, but there are lots of "web-bot" examples documented on the Web itself. E.g. do a search for "ruby web bot" or similar depending on your level of coding skill and interest.
In any event starting with a manual regime will give you an idea of what is useful.