Priorities - resets the Weapon Priorities . You may find after playing F.E.B.A. or any other mod that may introduce new weapons that UT will not automatically select the correct weapons. This button will fix this problem for you. If you get smoked, this process must start all over. Experience points are not retained.
Higher Levels mean different things for each class.
Harbingers become faster while Commandos get stronger. Now, there are a lot of complex attributes that dictate Player Class behavior. In traditional RPGs, you see things like Dexterity and so forth. Each player class has a detailed description stating their role in the context of F.E.B.A. gameplay and certain special abilities. There are a lot of factors that should influence you to pick a class.