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
B. P. D. Consulting                  (714) 632-3841 Phone
2034 E. Lincoln Ave. PMB #344        (800) 828-9578 Toll Free
Anaheim, CA   92806                  (603) 452-8504 FAX