I'm new to firefox so sorry if this has been covered.
If I have bookmarked url's there is no way for me to remove them using shift + del like you can on some other entries in the URL suggestions dropdown menu. This is annoying because I have custom searches set up (ie I type "you" then push tab for it to search youtube) and these do not work as some other suggestion will jump the queue and I will then open the website that firefox pushes to the top. This only happens if i type fast, if there is a pause then the custom youtube search will work.
More control over URL suggestions including the ability to delete bookmarked url's from suggestions would be nice, I already have them bookmarked and pinned up top so don't need them to be inputted into URL suggestions.