Try installing the latest update. After doing that, if the buttons are still missing, manually run CC3MenuConfig.exe found in your CC3+ data directory.

You.

Remember, you can search for text in maps using either the atlas online search, or by the search in CC3+ itself using the atlas index.

You should be able to assign the command

DRAWTOOLSM drawtool name;

to a menu button.

Likewise

FSTYLE fill style name;

should set the current fill style.

See this article about menu editing for doing the actual menu changes.

Do note that menus aren't style sensitive, so the buttons would only work properly as long as the current style actually have a tool/fill by that name

1. Generally don't overwrite things, make a copy and edit it instead.
2. There are a lot of things you can change from within the program that you could make a backup off, such as Symbol Catalogs (.fsc files, live in the @Symbols directory), Drawing Tools (.dto files, lives in @System\drawtools), templates (*fct, @Templates), symbol catalog settings (.sis, @System\Symbol Catalog Settings), Symbol Catalog Master Filters (.sif, @System\Symbol Catalog Master Filters)
3. No. There isn't a way to reset other than reinstall or restore from backup.

Note that the files you are most likely to change (accidentally) are drawing tools. Symbol Catalogs can only be changed by loading the symbol catalog as a drawing (instead of into the symbol catalog window) something most people don't do and pretty much guaranteed wil never happen accidentally. Same with templates, you need to load these as a drawing to change them, changes in a drawing never change the template it is based on. Symbol catalog Settings are also somewhat easy to accidentally modify, if you click advanced in the select symbol catalog window.

Things that only affect the current drawing are changes to fill styles via the Fill style dialog, as well as editing symbols via the symbol manager. The latter only edits the copy of the symbol in the drawing, and not the global symbol catalog.

The reason for this is that the hull is a massive polygon below the deck polygon, so there isn't really and edge here that can cast shadow as far as the hull is concerned. And the deck itself is set up to cast a shadow, but shadows extends outwards from the caster, not into it, you can see you have a shadow from the deck in the lower right of the map.

What I would have done here is to use a black glow (set to inside) on the Deck sheet, and disabled the wall shadow on it.