If I'm only 17 and go to the gynaecologist for possible cysts/absent periods will they do any exams besides for an ultrasound?

You want a good exam. In order for you to find out what's going on, you want to get a good exam (that's why you go to the doctor). Hopefully, the doctor will check all the external "girl parts" to make sure all such parts are properly developed. Whether or not an internal vaginal exam is done will depend on one's individual symptoms (different girls have different symptoms). Be brave. Blood tests might be ordered.