Reply #4: In some states, an employer can be a "union shop."

[The Velveteen Ocelot]

That means the union legally represents all employees. Sometimes you can opt out of joining the union (depends on the state), which means you don't pay dues, or you pay reduced dues, but all that means is you can't vote at union meetings. You still are bound by the union's collective bargaining agreements. The answers to your other questions (dues, etc.) depend on the contract the union has negotiated with the employer. The benefits to belonging to a union are (among other things) that you can't be fired at the whim of the employer; you are guaranteed certain pay rates (usually higher than if there were no union) and benefits that the employer can't take away just because they want to save money; and if you are laid off you have recall rights. If there is a strike, however, you would not be paid for the days you don't work (though some unions have strike funds), and if you crossed a picket line you would definitely be considered a scab.

The union probably has a web site that could answer your more specific questions.