Search parameter optimization

I am using postgres to search databases with 1.75 million records. It's a
yellow pages database. I read through the mailing lists and learned how to
use the lower function to speed case insensitive searches, but am still
getting some results that don't make sence. For example:

select * from ca where lower(company) like 'baskin robbins' and lower(city)
~* '^anaheim';

executes 10 times faster than

select * from ca where lower(company) like 'baskin robbins' and lower(city)
like '^anaheim';

even though

select * from ca where lower(city) like 'anaheim';

is faster than

select * from ca where lower(city) ~* '^anaheim';

I have issued a "vacuum analyze ca" command.

How to I get the fastest search results from complex expressions?

Is varchar or text better or is char better even though it takes up more
space? When searching a 5 digit zip code is char or int better?

-----
Bruce De Vries, Proprietor http://www.bpdconsulting.com
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