What is the ruling on registering in a forum that includes men and women, writing diverse things such as supplications and funny anecdotes, and using expressive emoticons in a personal blog?

There is no objection to women participating in mixed forums if they do not include anything prohibited. It is preferable to utilize the time for beneficial activities such as inviting to goodness. As for using smiling or astonished emojis, which are merely a head without a body, these do not fall under the category of prohibited images.