Every doctor is different--unfortunately. Some just want you to do all the talking and they will do none at all, while some like to ask you questions and not have you elaborate, and some ask you some starter questions to draw you out and then listen to everything you say, even if you go off on a tangent (these, in my opinion, are the best kind of doctors).
Trust me, you will forget a lot of your symptoms and questions when you go in due to nerves or the doctor's questions leading you away from them. So I would suggest you write down your symptoms as specifically as possible, such as what foods make you worse, when and where do you hurt the most, what medicines seem to help, etc.? And if you have questions now, make sure you write those down on a separate piece of paper and ask them once you have gone over your symptoms. If the doctor says you need tests, be sure you ask him why he thinks you need them, what they will show, how they will work, etc. Don't let him leave you feeling confused and befuddled. Make sure you give him your list of symptoms to put in your file, just in case you didn't go over everything or he missed writing some of them down.