I'm a little confused

why elgg does not have more templates done from professionals, and some list of like core plugins.For example , some trusted plugins or recommended from elgg team, something like that.
I want to start developing plugins, i dont now from where to start.

  1. Can u post some shortcut or best practice?
  2. uninstalling plugin is just removing from mod directory?do i need to clean database?
  3. how to validate user directly in database (i was importing from joomla and i had validating problem)
  4. that's it for now.