I've never applied Debevoise but if it was me, I think I'd spend the first question elaborating more on the work that the firm does and maybe the second question on the kind of personal/professional development opportunities that Debevoise in particular provide. I've just had a look at the GR brochure and this are some points in their "fundamental values" section:
- Recognition of the importance of the quality of our lives and of the need for balance and mutual support to deal with the pressures of practice and our lives
- Strong commitments to public service and public responsibility, equal opportunity and the improvement of our profession - This could tie in very well to the huge emphasis they seem to have on pro bono work. I know from attending an event with SEO that they have an online magazine written/edited solely by the women at the firm that (which I thought was pretty impressive) discusses a lot of gender equality issues in the professional world
Maybe thinking about how these values link up with anything you have demonstrated matters to you (through anything you've done at university or otherwise)/ what you want from your career will help.
Sorry if this is a bit vague, just thought I'd drop my thoughts anyway!