"giant structure" merely means that it is a continuously repeating crystal structure, with no defined number of atoms
1. : Ionic bonds are NOT covalent. Simple ionic bonds that create crystal lattices are giant. Ionic bonds (with formal electron transfer) that form no such endlessly repeating lattice are not giant.
2. Read the definition; if a larger superstructure is created where you have a continuously repeating unit cell without being able to exactly pinpoint the number of atoms present, then it is giant.
3. try reasoning yourself on this one first. What would be the difference properties between a superstructure and a chaotic mixture