A. An interview is a two-way street. An eager candidate that acts desperate enough to accept a job without research comes across as just that -- desperate and/or insincere.

It sometimes happens that the company extends a job offer to the candidate, who declines to accept it because of something s/he's learned during the interview. This is better for both sides, than if s/he took the position and resigned in a few months.

Don't assume that the second, third or fourth interview is just a formality, even if your prospective superior told you so. You can give such a bad impression to your superior's superior that she'll veto his choice.