Hi there and welcome to Blender Artists 
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I hope you enjoy using the site, and I hope you enter the weekend challenge at some point.
I have been participating in the weekend challenge for about half a year now (I think), I wasn’t around here on Blender Artists for the old challenges, but I think I can probably help.
Regarding the polls, I am not sure why that has happened, it’s probably something to do with updates breaking older versions or something like that, but I don’t know, @bartv or @joseph might though.
The images, I think years ago the hosting for the weekend challenge was done differently, and by the looks of it everybody uploaded there renders to their own website, most of which have now gone offline. I don’t know when it changed, but it seems to be about 2006 from a quick look that people started uploading the images to BA.
If you look at the original rules from 2002, you can see it says:
Third, a link to the entry image. A link directly is preferred, although a link to a page containing only the entry image is permitted. A “copy and paste” warning should be given, is necessary. Optionally, a thumbnail may also be supplied. The link and optional thumbnail will appear in the entry list for voting.
So, it looks like people where encourages to use cloud storage or there own personal website.