Hi,
- You need to scroll down in the elements window to be able to see it.

2a) It could be possible with custom development, but this would be outside the scope of support we can offer. You may wish to consult a developer to assist you with this. X is quite extensible with child themes, so there are plenty of possibilities.
2b) You need to create another menu in Appearance > Menus with no dropdowns. Then add another navigation dropdown element and select the menu with no dropdown.
After that, make the element to be only visible in mobile.

That way the menu with dropdowns will only show in desktop and the menu without dropdown will show in mobile.
Hope that helps.