Do you really need to have the 'ett' in this sentence?
No you’re right, the article can sometimes be left out.
Can one say "i restaurangen" for "in the restaurant" and have its meaning stay mostly the same?
'Boka', 'reservera', 'beställa' and 'tinga' - would they all work here?
I got "jag reserverar ett bord på restaurangen" wrong
"reservera" should work here, imo, though it's a bit rough. As for the other ones, I think not.
may you fix the Numpad functionality for multiple choice questions?