Item 1: Don't know of any. It'd be an interesting project to set up though...
Item 2: Define an extra text field that auto-enters a concatentation of kA and kB and set a unique values validation on it.
Item 3: This can be done, but I wouldn't call it simple. In filemaker you can refer to table occurrences on your graph that are more than one remove away from your "starting" table occurrence and you can combine that technique with a relationshp that uses either calculation or global fields to specify your aVal and aVal2 quantities.
In terms of 2. , I'm assuming you use a calculation to create the concatenated key, but I can't see where you can get into the field options dialog to give it unique validation. Or is there some other way of creating the concatenated key?
It's not a calculation field. It's a text field with an auto-enter option selected to enter a calculated value.
Double click the field definition in Manage | Databae | Fields and then click the auto-enter tab in the dialog that pops up.