Please edit your post to correct the formatting. See Markup in the Monastery. You should at least use <code> tags around your config file so that it can be displayed properly.

The "search and replace from a list of replacements" part can be done using a hash, and the substitution operator.

use strict;
use warnings;
my $text = "I will not stir from this place, do what they can.";

my %replacements = (
                     "will not"         => "won't",
                     "stir"             => "move",
                     "this place"       => "here",
                     "do what they can" => "let them try");


my $pattern = join "|", map quotemeta, keys %replacements;

print "The pattern is: $pattern\n";
my $replaced = $text =~ s/($pattern)/$replacements{$1}/gr;

print $replaced;
[download]

The pattern part is a regular expression if you don't know about them you can look at those tutorials.
The quotemeta escapes the special characters in the search items so that they are interpreted litteraly in the regular expression.
The s/search/replace/ part is what does the actual job, the search part will capture the strings it finds (because of the parenthesis) into $1, and $replacements{$1} will return the matching replacement. The g in /gr means "general", and will apply the change everywhere in the string, not just once, and the r means "return", so the result is returned to $replaced, instead of changing $text itself.

As for reading your config file, one of the config modules might do what you want.