Off-python-topic: Cron jobs on linux...help

[Chris Richard Adams]

I'd like to ask two things about the cron tool that comes with Linux -
have RedHat 6.2.
 
1.) I have a script that runs fine when I am logged in a the user who
owns it.  I have env variables that are needed and these are loaded in
the .bash_profile as that user logs in.  As that user, I set a cron job
putting the pathname of the script.  It runs, but fails because it
appears the  environment vars are not set.  I can work around it by
putting all the vars in the script of course, but what might be the
problem?
 
2.) I want the script to run each 20 minutes.  With only the 5 time
parameters to set, I can't do this?
 
Thanks!