A deb is an ar archive, with a magic number of !<arch>, consisting of three files. The first file is named debian-binary. It is a text file with a series of newline separated lines. Currently it has ...

No, those packages are just used to save download times with apt-get. It's completely harmless to remove them. If you do, it'll just be downloaded again the next time it's needed.

A file extension, or file name extension, is the letters immediately shown after the last period in a file name. For example, the file extension.txt has an extension of .txt. This extension allows the ...