1. Does google index these links?
In order for Google to index a page it needs to be able to crawl it. Crawlers are not able to activate functions on websites like 'search' or 'submit' buttons. Pages that you can only get to by submitting information cannot be indexed.
For example, if you enter a competition online, very often you will need to enter your name and email address and click "Submit". You are then sent to a page that says 'thank you for entering'. This is an example of a page that will never be indexed, unless somebody links directly to it. (and its not blocked by robots.txt, but that's another story)
In the same way, the crawlbots cannot do a search on Yahoo and then index the results page. The only way Google can index these pages is if somebody saves the SERP URL and then links to it from somewhere that the googlebot can index.
So the answer is yeah, Google indexes some of these pages, but only a small few of them.
2. Does Google give any value to them?
As Ronan said, search engines are just like any website, so their pages are just like any pages. It's unlikely that a SERP has a lot of inbound links (unless it's a particularly hilarious/interesting SERP) so the value of their link juice is unlikely to be very high.
Let me know if any of that doesn't make sense and I'm happy to clarify - reading back it is quite heavy!