There are CPAN modules to solve every one of your stated problems.

1.In a file how do I change the numeric values to word excluded the date format

Use Lingua::EN::Numbers.

use Lingua::EN::Numbers qw(num2en);

while (<DATA>) {
    s/(\d+)/num2en $1/eg;
    print;
}

__DATA__
Too Small: 7 and 5.
Too Big: 123345
Just right: 51
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2.How to capitalize the first letter of each word found after AU: marker

Already asked and answered in it's own thread Make the first letter of each word capitalize. Just use Lingua::EN::NameCase.

3. there's a date format Oct 27, 2011 change to YYYY/MM/DD output should be 2011/10/27 I having a problem how to change the month in numeric form first then change the format as YYYY/MM/DD.

Use Date::Parse and POSIX:

use Date::Parse qw(strptime);
use POSIX qw(strftime);

my $str = 'Oct 27, 2011';

my $newdate = strftime "%Y/%m/%d", strptime $str;

print "$newdate\n";
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- Miller