To begin with, you don't need to email anything anywhere. You literally just turn up at the audition but make sure to bring your CV with you. The reason you need to bring it with you is because if by some chance you did make it through the audition, you would need to hand it in to them.
The layout of the audition is pretty relaxed. However, be aware that the audition room is pretty small so if there happens to be a huge turn out on the day of the audition then it will get quite cramped and possibly hot in there. Also, you will struggle to practice anything as you will just have no room to do it. So best thing to do is practice at home before-hand.
The auditions are usually split into two parts. The first part is called "animation". In this round you will be taught a movement routine. To counts of 8, they will ask you to act out a cowboy, pirate, one of the seven dwarfs, two villains, a prince/princess, and then as a general cast member. They will be looking at you for good animation and energy levels. My advice to you for this bit is to (if you can) be as big as possible with your actions, and show enthusiasm.
Then there is a cut.
If you are successful at this section then you will proceed to the second part of the audition, which is the dance round. You will be shown a basic-difficult dance routine which you will then have to perform to the judges. Remember to smile a lot during this stage and if you can't remember all of the routine then just make something up on the spot.
Then there is another cut.
If you are successful, you may be picked to go away and try on some wigs and makeup to see if you resemble any face characters. Otherwise, you have passed the audition as a Character-Only Performer or a Character & Parade Performer, depending on your audition results.
Now for the tricky bits...unfortunately, just because you are a fantastic dancer or performer, it does not mean you are going to get through either stages of the audition. At each audition they are looking for different things so if you are turned away at an early stage then it doesn't mean you were rubbish, it could just mean you weren't what they were looking for. Possible reasons for this include your height, body shape, and maybe even your face.
I have been to about four auditions now and every time got turned away straight after the first section. I did get the chance to speak to the casting director about why this was and he revealed to me that the reason I'm never successful is not due to my animation or anything, it is to do with my body type. Basically, I won't fit into the costumes of the characters I could play at my height. So as you can probably guess, if you are slightly overweight then they may have to discriminate a bit.
Hope all that helped you a bit and if you need any more questions answering then message me if you like.