...an apartment to rent?

Maybe. Personally I don't specialize in rentals so I tell people looking for rentals they're better off looking in the newspaper or contacting a company that specializes in rentals (I usually give them a phone number). Other areas are more rental-centric (I just made that word up) and a real estate agent might be the easiest way to find a home.

yes then they're doing the work of sifting thru what you don't want and getting you apartments to look at that fits your needs.

sometimes it is because they can generally get in to see people that you may not be able to get in to see on your own.

Yes, deffinetly a plus to use a real estate agent no only will they usually not charge you a fee becuae they collect it from the landlord, but they sometimes have more "pull" with the landlord to get there "client" in.