"Please…explain to me in simple terms how to make things stick once dragged and dropped in Pages?"
Objects placed on a page are automatically pinned to a location in the text, set to Move with Text, and are set to make text wrap around the object.
With this setting, adding text above the object will cause it to move to maintain the same position with respect to the point in the text to which it is pinned.
You can change any of these settings by clicking on the object to select it, then opening the Format inspector to make changes.
Click the Format brush, then choose Arrange.
Click Stay on Page to pin the object to the page (This actually pins it to a location a fixed distance below and to the right of the top left corner of the Section containing that page.). You can then drag the object to a different location on the page, and leave it there. Go to the Arrange menu and choose Lock to lock the object into position.
"Can I set edited chapters in stone (as in a pdf) within a 250 page document so that once it's to my liking it won't change?"
Text within a word processing document (whether in Pages or some other application) generally remains editable unless the whole document is made 'read only'. You can export the document to a pdf file via the Print dialogue. Click the PDF button at the lower left of the dialogue for a list of options.
PDF documents are editable in a PDF Editor, but less so in a PDF Reader.
"NB Apple…"
Apple provides the space for Apple Support Communities, but does not regularly participate in these user to user discussions.
For feature requests, use the Provide Pages Feedback item in the Pages menu to send your request for a feature enhancement directly to Apple.
Regards,
Barry