On the suit/tie question, it's not as clear cut as one might hope. I recently got feedback on an academic job (a lectureship post) I went for and was told that my suit was off-putting and gave off an unwanted corporate air. Although the other candidate got the job because of his/her willingness to take on managerial/admin roles, impressions do of course count.
I've always played safe in the past on the basis that one should appear respectful of the occasion. Apparently however the audience for my presentation were somewhat startled by both my outfit (navy blue, not luminescent green) and my presentation that I felt was confidently delivered. Surely it is not a prerequisite in academic posts to be nervy, squirmy and unconformable? Do I really have to wear linen and Jesus shirts?!