Thank you so much for posting this info! I did have one problem though.... I figured it out & thought this might help someone else.
Problem with ATTACHMENT - Can not find or see photo! (Paperclip -> browse -> upload.)
Reason: #1 Attachments appear at the bottom of the post.
Reason: #2 NO ERROR APPEARS!!! IT JUST DOES NOT POST. Maybe the KB (size in bytes) could be too large. All size limits are listed in Paperclip per file type (jpg, etc). Do not just check width/height is < 800 pixels/demensions. Photos can have a resolution which could increase the KB's of your photo's file. Even though it is an okay width/height.