Salts are the products of the reactions between an acid and a base.
All salts can form crystals.
Metals and ammonium form generally salts.
Yes. Salts can form crystals (salt crystals).
All acids form salts
The majority of elements, and especially metals form salts.
Practically all chemical elements can form salts.
Metals form salts.
Salts have different crystalline structures.
Metals form salts often.
Halogens are not salts but they are chemical elements; halogens can form salts reacting with metals.
Not all salts, particularly complex ones, form crystals easily. We have no idea how to form crystals of many salts, but that does not mean they cannot be made, merely that no one knows how to do this.
The family that combines with metals to form salts is the halogen family. There are other nonmetals that can be mixed with metals to form salts, but halogens are the most common.