I'm using debian/Ubuntu, and get confused about versions of packages. When using dpkg -l command, I get:

ii  vim                                 2:7.3.429-2ubuntu2.1                Vi IMproved - enhanced vi editor
ii  vim-common                          2:7.3.429-2ubuntu2.1                Vi IMproved - Common files
ii  vim-runtime                         2:7.3.429-2ubuntu2.1                Vi IMproved - Runtime files
ii  vim-tiny                            2:7.3.429-2ubuntu2.1                Vi IMproved - enhanced vi editor - compact version
ii  virt-what                           1.11-1                              detect if we are running in a virtual machine
ii  w3m                                 0.5.3-5ubuntu1                      WWW browsable pager with excellent tables/frames support
ii  watershed                           6                                   reduce superfluous executions of idempotent command
ii  wget                                1.13.4-2ubuntu1                     retrieves files from the web
ii  whiptail                            0.52.11-2ubuntu10                   Displays user-friendly dialog boxes from shell scripts
ii  whoopsie                            0.1.33                              Ubuntu crash database submission daemon
ii  wimlib9                             1.5.0-1~webupd8~precise             Library to extract, create, modify, and mount WIM files
ii  wimtools                            1.5.0-1~webupd8~precise             Tools to extract, create, modify, and mount WIM files
ii  wireless-tools                      30~pre9-5ubuntu2                    Tools for manipulating Linux Wireless Extensions
ii  wpasupplicant                       0.7.3-6ubuntu2.1                    client support for WPA and WPA2 (IEEE 802.11i)
ii  x11-common                          1:7.6+12ubuntu2                     X Window System (X.Org) infrastructure
ii  x11-utils                           7.6+4ubuntu0.1                      X11 utilities
ii  xauth                               1:1.0.6-1                           X authentication utility
ii  xbitmaps                            1.1.1-1                             Base X bitmaps
ii  xclip                               0.12-1                              command line interface to X selections
ii  xfonts-encodings                    1:1.0.4-1ubuntu1                    Encodings for X.Org fonts
ii  xfonts-utils                        1:7.6+1                             X Window System font utility programs
ii  xkb-data                            2.5-1ubuntu1.3                      X Keyboard Extension (XKB) configuration data
ii  xml-core                            0.13                                XML infrastructure and XML catalog file support
rc  xpdf                                3.02-21build1                       Portable Document Format (PDF) reader
ii  xterm                               271-1ubuntu2.1                      X terminal emulator
ii  xz-lzma                             5.1.1alpha+20110809-3               XZ-format compression utilities - compatibility commands
ii  xz-utils                            5.1.1alpha+20110809-3               XZ-format compression utilities
ii  zabbix-agent                        1:1.8.11-1                          network monitoring solution - agent
ii  zlib1g                              1:1.2.3.4.dfsg-3ubuntu4             compression library - runtime
ii  zlib1g-dev                          1:1.2.3.4.dfsg-3ubuntu4             compression library - development
ii  zsh                                 4.3.17-1ubuntu1                     shell with lots of features

The third column is version, but it all messed up in a way I can't understand. I mean, different packages use total different naming specification.

Here are the major questions:

1. Why there are ubuntu in them, and there are not?
2. what all the special -~+ mean?
3. alpha and build, dfsg, what are they? Can I just use them casually?
4. vim and other packages have 2:, what does that mean?
5. How version comparison works, since they can be so different?

Can anyone please explain this to me? Or where can I find an official document?

Thanks in advance.