Well first of all, to become an intern you need to talk to your STL and ETL-HR and see what they say, you will need to be about a year or two from graduating to be considered... You will have to turn in an app and interview, most likely with different people from the campus recruitment team! If you pass interviews, you will have to "quit" Target and basically be rehired as an intern... You most likely will move stores at that point and go to wherever they want you to within your district to train... The internship is a 10 week training program, and afterwards they will decide if you can be an ETL or not after you are done... Usually summer is over at that point and you go back to school, if you want to work part time during school you can, which is awesome because you are paid your intern wage doing TM work (usually around 15 bucks/hour)... After you graduate you will be sent to business college...
Business College is 6 weeks of training, half class room and half with your business college trainer in a store... You basically just get trained to be an ETL, but since you did the internship you will have a good idea of what is going on already.
The ETL - Guest Experience is an ETL only in B and higher volume stores. They are in charge of all things guest experience like people said, the front end, carts, guest service etc... but also they are in charge of the guest experience in all of the store! If electronics service is bad, if the salesfloor speed scores are low, they will be in charge of those as well!