Customize Wordpress Directory Theme

I am creating a directory website using a theme by AITthemes called 'Directory+'. These are the customizations I need done to the site:- 1 - Login / Register button at top bar (right corner). Clicking on it will pop up a sign in / registration form. There is an login / register element in the theme in pagebuilder but it can only be added to the 'body' of a page. There is a login / register link at the footer menu linking to a page with this element to show you how the element works. 2 - Need a front-end add a listing form - The theme works like this: The user has to login and then they will have access to an area where they could change their profile info, add / manage listings etc. I need for there to be a form where unregistered users could just add a listing by going to a page and then filling up the form and then submitting the listing. The form would also create an account for the user. 3 - Need the claim listing tab to be located below contact owner tab in item pages. Also need the item info to be arranged in a presentable way (up to the programmer - i'm not very particular about the arrangement, just need it to look presentable) 4 - Need to be able to limit categories based on package type 5 - Need documentation on the work done - changes, additions to code etc - the theme is new so there are auto updates (using a plugin) to the theme every week, so I need to know how to add these features back every time there is an update (as it would clear the changes). 6 - Questions / suggestions are welcome. Thanks!