I'm going to assume the medical rules are pretty similar to the UK, but in short, disclose everything. Your AME will decide what is relevant or not. They almost certainly won't care about your appendix removal but you still need to disclose it.
If you can, bring any applicable medical records relating to anything you select yes for. Your doctors surgery should be able to provide you with a copy of any such records (or the whole lot of that's easier), but give them as much notice as you can. If you can't bring the records to your appointment, I suspect the AME will ask you to provide them as soon as you can or refer you to a specialist to provide a report. This will be at your own expense!
Keeping in good shape and maintaining a good diet is a good idea for the medical, but also to avoid complications for future ones. I've heard of people advising to avoid large meals and large amounts of caffeine before your medical as this can affect the ECG. I hope that helps!