Correct and Debug Wordpress Script, and Convert To Plugin

Hello, I am a 71 y.o. Non-coder. I have been trying to develop a script for use on a Wordpress Multisite Network. My subscribers will be offering services on their subdomain home page. I have prepared sales pages as posts for them to use, but they are limited to only four sales offer pages. (Which are, in Wordpress terminology, actually “posts.”) They select which service they will provide from a list, which represents posts or sales pages. They are also allowed to modify the description slightly, set guarantee terms, and the price. After they have selected the post, and saved it, a copy of the original is placed on their site, overwriting one of the existing offers already on display. The original remains untouched on the main blog. Thus, a limit of four offers is imposed and the admin is free at any time to change the offers they present. Most of the script works, but I am unable to complete the work. I am attaching the script as I have developed it so far. The offer selection and modification screen is presented as a widget (or metabox?) on the site admin dashboard. Therefore there is a code snippet from my themes [login to view URL] file, along with the code that is implemented in that widget. The problems I am having are: (1) The save button does not appear to be saving the correct file. It appears to be saving the last file through the loop that creates the selectbox used to choose the files. (2) The thumbnail image for the active offer does not show when the widget is loaded. It should show the thumbnail for the current offer on load, and the current selection under consideration after the choose button for the selectbox is clicked. (3) The widget is not secure. I have not added sanitizing code. (4) I would also like the script converted from an admin page widget, to a plugin. I could probably do this myself, after the functionality is straightened out, but it might be simpler for you to do it all at one time. This script has approximately 175 lines of code, and can probably be completed in less than 200-225 lines. I can provide a testing environment on the site where the script will be used. A moderately skilled wordpress/php coder should be able to correct errors and provide a working product in less than eight hours of coding. The attached file includes the function and hooks I used in the theme [login to view URL] file, as well as the widget code.