Lycanthrope help

[Truwen]

So my group is getting a new player. I am introducing her as a Weretiger rogue. She is an afflicted weretiger, so my question is this. She was afflicted around level 6, does the weretigers HD add to her class level? Ultimately effecting her experience gain?

Looking in the basics tab at the Class levels section with level 1 rogue and then 2-9 weretiger template.

Next level: 10 (45000 XP to go). Is this how this works? I just assumed she whould gain the HD of the weretiger (gaining more hps, abilities, damage reduction etc) I didn't expect it would effect her rate of leveling.

At any rate I need help on understanding the Lycanthrope rules/how to apply the affliction to an already leveled character. (Keep in mind the class and levels above were just for example purposes and I don't currently have her character inputted into hero lab).