Which one of the 12 members of Group B can be added to the 7 members of Group A? Why?

Group A: Arizona, Maryland, Nevada, Oklahoma, Pennsylvania, Tennessee, West Virginia
Group B: California, Delaware, Florida, Georgia, Iowa, Kentucky, Louisiana, Maine, Missouri, New Jersey, Texas, Wisconsin

Which word in Group B can be added to Group A?

Group A: castanets
existence
kowtow
venomous

Group B: gardening
lucky
mountain
restaurant

What is the next state in this series?

New York, Maryland, Georgia, Maine, Texas, Louisiana, North Dakota, Idaho, ?

Which president in Group B can be added to Group A? Why?

Group A: Andrew Jackson, Zachary Taylor, Ulysses Grant, Dwight Eisenhower
Group B: William Harrison, Theodore Roosevelt, John Kennedy, Lyndon Johnson, George Bush, Bill Clinton

Which country in Group B can be added to Group A? Why? It has nothing to do with spelling or pronunciation.

Group A: Argentina, Iran, Jordan, Netherlands
Group B: Bolivia, Finland, Mongolia, Pakistan, Rwanda, United States

Anagram teaser; same letters, of course.
The first of the words is the movement of a horse.
The second of the words is used to make honey,
And the third is the look of a zombie.

What are the words?