ifconfig
To shut down an FTP server in Linux, you would generally use "ftpshut." The command syntax can vary slightly, so check your man pages for the correct syntax.
There are many FTP server packages in Linux, each with different configuration files and syntaxes. A single question trying to answer how to configure them all would be long and unwieldly, and would duplicate information found in a question about a single implementation. Please ask a question about a single implementation, such as vsftpd or tftpd, instead.
Linux dedicated servers do not offer packages. It is not a service that you purchase, rather it is a type of server that your service would be running off of.
init 6
mount
In order to zip a subdirectory in Linux you would use the zip command with the recursive flag to specify that it should add all files under that directory into the zip file. The command would then be zip -r .zip .
nslookup if it was a linux machine nslookup works too, but dig -x on a linux machine will get more info for you
In my personal opinion, No, a Linux server is the better answer for the web. I would recommend a windows server only when running asp/.net, and with the introduction of mono (an apache module), Linux machines can run .net (although I've never used this, myself, and it is in its infancy). Linux, in general, has much better thread and memory handling than Windows. In a multi-threaded web server, it should serve you better. Remember, that things like this are always a personal preference type of thing, and the debate between Windows and Linux is fierce. My advice would be to look up benchmarking information for Windows web servers and Linux web servers, and see which would suit your needs.
rmdir
If you want to shut down the computer, usually "poweroff" or "shutdown -h now" would do. If you want to exit from the graphical interface, you typically just need to shut down the X server (the graphical session generally runs through a display manager session or your startx command)
# kill -HUP pidwhere pid is the PID of the server process.
That would be a semi-contradiction; the command line would need to be already running in order to enter a command. The name of the program that actually provides the command line is called a shell. There are many different shells available for Linux, including Bash, ash, C Shell, fish, ksh, zsh, and scsh.The default command shell is /bin/sh (not /bin/bash, note).