How can I display a list of all rpm packages on the system with their sizes?

“rpm query size”

RPM (Red Hat Package Manager) has an excellent --qf (query format) option, which behaves much like printf function. Command rpm -q mozilla --qf '%{SIZE}
\n'
will display the size of mozilla package. To list all packages with their sizes, you may use something like: rpm -qa --qf '%-15{SIZE} %-30{NAME}\n' . The output of this command can be piped to sort -n to produce a list sorted by size.

How can I configure mutt to use addresses from LDAP addressbook?

“mutt ldap address”
“.muttrc ldap address”
“mutt ldap”
“ldap script for mutt”
“ms exchange directory”

You will need to download one of the LDAP querying scripts for mutt. One of them is here. After downloading, edit the script to match your LDAP server and put lines like set query_command="/home/username/bin/mutt-ldap.pl '%s'" into your muttrc file. If you will add also bind editor "\t" complete-query , then you will be able to complete addresses using Tab button.

Note, that you can use the same script with MS Exchange, since it’s nothing more then an LDAP address book. :)

How can I configure mutt email client to use koi8-r character encoding?

“mutt charset koi”
“mutt sending mail in iso-8859-1”

To make mutt use koi8-r encoding edit your muttrc file (usually /etc/Muttrc or ~/.muttrc) and add line set charset="KOI8-R" for reading and line set send_charset="KOI8-R" for writing in koi8-r character encoding. Your terminal program and your editor should be configured for koi8-r encoding independently/separately.