A: Not necessarily. These days many schools receive large numbers of applications from potential job applicants and it would be disrupting to allow them all to visit the school.
There is plenty of information available about individual schools on the web these days, from Ofsted, the DfES Edubase website and even the school's own site, even if there are no blogs from pupils or teachers.
If possible, you could also pay a visit to the vicinity of the school to get the feel of the area and how pupils move about at the end of the school day. Should you be shortlisted, and the school still refused you a visit, then I would be more likely to be wary.
Matching candidates to jobs is a two-way process, you must fit their needs, but the school must match up to your requirements.
Early in your career, many schools might meet your requirements, later you may have more specific concerns about the type of school you are willing to work in: round pegs are no good in square holes.