Theme a admin block without specify Block Id is better practice because local block id and server block id may be differ in that case we need to update our code. In some time we need same theming for multiple block,
When implementing Views in websites, you might come across situation when you cannot find the proper field to display the data. Finally we end up using a php field for displaying the data. Use of php field will always affect the caching of the views.
For creating the custom pane and using inside the panel, We need to download and enable ctools and panel modules. For downloading and enabling the module we can use drush command or download and paste inside the modules folder also