1. "post content" means the text inside of your initial post (see how you reply to a topic? that's your post data).
2. "inline" images are images that show with an image tag in the post, showing the image to everyone; the image will show inline based on two variables. A. It must be under the "max inline image size" set in the control panel, this is to stop users from uploading very large images and expecting users on slower connections trying to load them all. B. the filetype must be set in the control panel as well to be displayed inline (I think the default is jpg, jpeg, gif).
The attachment options can be located in the CP as:
CP -> Master Settings -> Feature Settings -> Attachments Tab
- Allowed Attachment File Extensions (.gif,.jpg,.txt,.zip,.png)
- Maximum Attachment Size (Maximum Attachment Size)
The "inline" options can be located in the CP as:
CP -> Display Options -> Primary Tab -> Topic Display Options Dropdown:
Max Size for inline uploaded images
