What are some entry level jobs in the airline industry I could get where I'd be able to travel internationally often?

If you like to travel airlines sales is a great way to do that. Being a Airlines sales person means that you travel to your accounts in your region. As I work for Cathay Pacific Airways I also travel to Hong Kong and other Asian countries.

The easiest will be Cabin Crew for an airline that travels internationally.

Any job with any airline will allow you to travel for pleasure at greatly reduced cost. All airlines have "interline" agreements with other airlines, (depends on the airline) where you can purchase reduced fare tickets, (most of the time for just a processing fee or like 10% of the regular fare). These are usually "space available." i.e. there must be an open seat or you do not get to go.

If you like to travel, the best way would be to be on the flight crew (Pilot, Flight Mechanic, Flight Attendant) doing international flights, or aircraft mechanic.