Is it possible to send PMs to other users on here? I looked all over two different users' profiles, but I couldn't find an option to PM them. Am I missing something? Thanks in advance.

You need more posts for unlocking the PM feature, but right now I don�t know for sure how many exactly.

You only need two posts to be able to send and receive PMs. You're already half way there at the time of writing this. One more to go!