dynamic formulas in views

I have two forms that are linked by a lookup field. I also have a view based on the first form, the one that contains the lookup field.

In the view, I can access the fields from both forms.

Is there any way to show in the view the calculated difference between the value of a numeric field in the first form and a numeric field in the second form? (So that if either value is changed, the 'difference' will be reflected in the view)?

Also: if the second form is linked to a third form by a lookup, I can't seem to access its fields in the view. Any way to do a secondary lookup in a view?

Hope this is clear - thanks for any help!