I am new to Linux and I am trying to create a cheat-sheet to help me remember common bash commands. If you know any of the commands for the tasks below, please post them. I appreciate it! 

Commands for: 

1. the hostname of the system you are on?
2. the type and version of the operating system the machine machine is running?
3. the full path to your home directory?
4. which other users are logged into the machine you are using?
5. the last five commands executed by anyone from /usr/bin?
6. how many words there are in the spell check dictionary (/usr/dict/words)?
7. what groups you belong to?
8. what files (excluding directories) are located in your home directory and all its subdirectories?
9. what man pages have references to 'bash'?