1. The order would be: aptitude/motivation/ attitude/previous exposure/learning style/personality.
The first three factors are the most important in causing mixed ability.The ability of every student to grasp the new language along with their willingness to learn and improve really make a difference in the group.
4. Mixed ability groups are ok if the teacher works with small groups but with big groups is a real problem because it is very difficult for the teacher to get to all the students. There are some positive aspects of working with mixed ability groups: You work with them on values like generosity and cooperation since they help each other in the group to do the activity together. Some of the weaker students get more motivated in these activities and their attitude towards the subject changes and they become more positive and receptive in these lessons.Yet, higher level students usually have to slow down their usual pace to help the weaker students, they do not learn as much content as they could and end up finding the activity unchallenging and they lose motivation.