Diagnosing...
If you're going to a legitimate specialist for autism spectrum disorders they will do a lot more than just fill out an autism questionnaire with things like "Do you prefer objects or people?" Of course it's quite easy to fake something like that, give answers you know would or would not qualify you for autism spectrum disorders.
Some of the things they will probably have you do is look at pictures of people and try to figure out what they're feeling or thinking. They'll ask you a lot of questions about your history, how many friends you've had, if you've ever had a relationship. They'll probably talk about school and work history, and see if you've had any problems adjusting to "the real world". Also there's a lot of observation going on, and if you have a 5 hour interview like I did it's pretty hard to fake being normal or being autistic for 5 hours straight.
So no, I don't think researching is a bad thing, and I don't think it should interfere with your ability to get a good diagnosis.
