I am a little confused at this one point:

# Razor give very good result and reliable to identify Spam mail
# Comment line below, if you don't want to change the score for razor2
score RAZOR2_CHECK 0.00 6.50 6.50 6.50

So does that mean it is best to leave that as-is, or is it best to comment it out?

Thanks!

If you use the default score for razor, spamassassin will score email at 1.90 (not sure but around this number). As razor is really good to identify spam, and very low false positive, I increase the score number to 60% of rejected threshold (12). Most of spam mail get rejected because this.

You can try to increase the various options such as:

score BAYES_99 0.00 3.00 3.00 3.00

This is a mail that Bayesian database give 99% confident that it is spam.

Okay, thank you.