If I have a three-word keyword phrase such as - wireless video surveillance - do all of these words have to be in the search in order for me to generate an impression?

Rating: +1

AdWords Help has a number of topics about how the Broad Match feature
works, check it out here: http://adwords.google.com/support/bin/topic.py?topic=10974

If you are interested in finding out exactly what people are searching
for I would recommend using the Exact Match option. This option
allows your keyword or keyword phrase to only display the
corresponding ad if it is the exact term someone searched on. For
example if you had the Exact match term 'wireless video' and someone
searched 'wireless video equipment' your keyword and ad would not
recorded an impression because it wasn't exactly what was entered in
the search query. To use the Exact Match option you place your
keyword phrase in [ ] ex, [wireless video]. However, utilizing this
function will cause the number of ad impressions to drop.