Queestce,
The testing is mostly maths/logical reasoning questions. There are some aviation based questions. However, I wouldnt worry about trying to find pilot aptitude tests to practice, they usually cost money and aren't really going to prepare you any more than standard aptitude tests. Just google maths aptitude testing and do some practice tests online. If you can get quick at mental arithmatic and logical reasoning this way, you can easily apply your abilities to aviation based questions. That was my findings anyway. My main problem in the testing was solving a given problem, answering the question but feeling the urge to double check it before moving to the next question. You dont have time, quickly solve the problem, go with your gut and move on to the next question.
I dont remember there being comprehension but there is abstract reasoning.
The hand-eye coordination testing is hard to prepare for, I reckon you've either got it or you dont. I guess playing games on xbox360/PS3, especially actions games, where you're using both thumbsticks on the controller will increase your dexterity somewhat (and will make studying more fun!).
No interview and no medical, thats for assessment day.
pacificjet,
The answers to all those questions can easily be found on the DFR website, you need to do your research. Also, if theres anything you're unsure of, call them and a recruiter will point you in the right direction, a phone call also shows your motivated.
Hope this helps!