I wouldn't worry too much about the nofollow link, especially since having a complete lack of nofollow links in a big profile would be a warning sign of link manipulation.  Still, Google also knows when a site with really high trust and authority uses nofollow links to maybe a too high of a degree--like wikipedia. That said, they also can bring search value.  See: http://a-moz.groupbuyseo.org/blog/the-hidden-power-of-nofollow-links and the first comments at the end of the post.  Cheers!

Why not change the file name to 'red-for-truck.jpg'? That would probably have a more positive effect. Much of what dictates image optimization is the same as on page factors, as described here: http://a-moz.groupbuyseo.org/blog/is-optimizing-photos-more-important-than-you-think. (On page factors: http://a-moz.groupbuyseo.org/learn/seo/on-page-factors) Plus Google has its own guide for image sitemaps here: https://support.google.com/webmasters/answer/178636.  Cheers!

In general it's a best practice to noindex the thank you pages as people landing on them from outside of your conversion funnel will trigger false goal completions. No following them is fine as well since they're a low value content wise, but ideally you want to make them as hard to stumble upon as possible. It's a good idea to remove them from the sitemap too if they've propagated there.  Cheers!

I'd say it's mostly transferable as plenty of content is found in both news and the main index. News is more of a service overlay that attempts to better handle user expectations for frequency and speed of response when it comes to news items. Still, old news gets into the index and treated like content from most any site so if you have a subscription based model that aligns with what they're recommending for more news orientated sites, at least you're fitting into a form of what they outline.

As an example, the New York Times does this via tracking of how many full articles a user reads while allowing Googlebot full access to its articles.  Sites that use this method employ "no cache" on Google so articles can't be read there and then various forms of tracking to ensure users are being counted correctly.  Here are some thoughts on this and more from Google's side that might help you out: https://support.google.com/news/publisher/answer/40543. Cheers!