Thanks for the kind words! ^__^ Controls remapping could be a bit messy to lift in, since every key interaction in the game uses the input system instead of standard GM keyboard events... so if you've got five thousand keyboard events spread over every object in your game, it would be some work to refactor them all.
The options menu should be a bit easier to lift in, but there's a lot of stuff you need to lift in: all the GGUI scripts (for the menu system), the horizontal, vertical and grid menu objects (and their parents), and all the relevant menu initialization and event scripts (and also mcb_optionssettingchanged, which is run when an option-menu setting is changed). And then the options_apply() and options_save() scripts to handle the options settings themselves... Thankfully, this should be pretty easy to import with trial and error. Once you think you've imported everything you need, try running the game and browsing through the options. You should get error messages along the way if you missed any objects or variables.
The options themselves just alter global variables that the various systems use (like the music and sound-effect volume variables which are used by the bgm and sfx scripts) so it should be pretty simple to deal with and extend.