Salutations, I will help you with question 1). 5 Shamans is very versatile. It is the reason why I chose that class. Also, in the future if you feel they are not sufficient to do some of the harder instances, then you can always sub in another class. They are great burst damage and this combines well with the heals, making it one of my prefered instance classes. I highly recomend it ^^.

Hope that helps

Qlimax