I haven't been notified about merging + other stuff

Okay, I uploaded a few hours ago this image and I didn’t receive the notification about that it was merged.
 
Also, despite that the artist tag says that there are 4 pictures and it even appears on such picture the name tagged, for some reason I’m only able to see the other three images of the artist but not this one of Twilight.
 

 
Also, I wanted to create this thread and this appeared:
 

 
What does it mean with “few accepted posts”? Do I need to have more posts in order to not receive such message?

To answer your question about the captcha, yes, after a few forum posts you should stop seeing that. It’s a way to weed out spambots, which the forums are a prime target for.
 
As for the image not appearing, sounds like you might have a tag (or an alias of a tag) in your filters, such as bedroom eyes or some such…it displays fine on the default filter.

@Aureai~  
@WingbeatPony
 
Oh - yes, with only 3 forum posts, you’ll still be getting Captcha for a bit until you have an established posting history. I don’t know what the cut-off is, but it’s not much - like, maybe 10 posts.
 
Also, when uploading images, the image doesn’t appear on the site except for the “still loading” page that is presented to the uploader for several minutes, to allow people time to finish adding spoilers and other tags that are important for filters.
 
If you are using the “Everything” filter and still can’t see all four images, let me know which images you see and I’ll try to look for clues.