If I do not add the attachment to the post, and save, it is not displaying as a thumb at the bottom like in 3.4. Is this correct or a bug? I can see a lot of unused attachments taking up space. Does an orphan task take care of these?

That's an interesting question.  

I've uploaded 50 photos totalling 6.72MB to waste IPS storage space but only posted 1 of the photos into the editor.   

Exactly. And admin never know. This could even be malicious if members want to fill up the server.

Hiding pics from view is not a good idea. Especially when the intent is to post. They could be unwittingly hidden or members could get in the habit of uploading an album's worth and choosing what they want from the thumbs and saving. And the wasted resources are hidden. If the thumb is there they won't do that, and if they uploaded something by mistake, they would see it in the thumb. Bringing the thumbnail back or a remove orphan task should be considered. Or is this a bug?

Exactly. And admin never know. This could even be malicious if members want to fill up the server.

Hiding pics from view is not a good idea. Especially when the intent is to post. They could be unwittingly hidden or members could get in the habit of uploading an album's worth and choosing what they want from the thumbs and saving. And the wasted resources are hidden. If the thumb is there they won't do that, and if they uploaded something by mistake, they would see it in the thumb. Bringing the thumbnail back or a remove orphan task should be considered. Or is this a bug?

another thing thatmight help is atool that can find all unused images or files

Or they should be removed/deleted when you click Save if not in the actual content. But then again having the option of displaying thumbs instead of full size in post was pretty cool.