Is there a way to see all the posts of people who I've noticed have very helpful explanations?
You can do a google search on their username and Duolingo. Other than that, there's not really an effective way to do so. There used to be an activity feed for each user, but that's been removed.
Other than ones that are always visible in the Duolingo forum, you may have to actively search for them, unless you followed certain discussions that are helpful. Just use the search bar to look for certain posts that have explanations (depending on what explanations you're wanting) and hopefully you can find the ones you are looking for specifically. Many times, people reference links to helpful posts, so if you come across people referencing the same link, then that one is most likely helpful and with the best explanations. ^ ^
No :-) but why would you like to do so? If you have a specific question you can use the forums search engine (ieek) or google (add duolingo to your query) (ook) for finding a useful answer.