Customize Work Item Fields

Hi, I have two questions for us:

- I would fix the choice of certain items of work item according to the values of other items.
For example for Defects I have fields A and B. Possible values for the field A are A1 and A2. Possible values for the field B are B1, B2 and B3.
When the user selects A1 I want to be shown that only the values B1 and B2 for the field B. This is possible in Jazz 1.0?

- It's possible (in Jazz 1.0) turn certain fields mandatory only when switching from one state to another? For example, when switching from Closed to In Progres, I would make some mandatory fields that, when you open a new work item, they are not.

Thanks
Andrea