In Drupal 7 you have entities and fields, fields are attached to entities. A node is an implementation of an entity (the node module implements hook_entity_info() and other such hooks) so it can have fields.
Drush commands are provided for managing the migration process. Individual migrations can be imported and then rolled back. Running processes can be cleanly interrupted, individual source records can be migrated on their own, and performance can be instrumented.
When working in the Views module, you may want to preview the SQL that is generated by the view. This is for the code savvy or the ones looking to be and would like to see the SQL generated for either debugging or further development of their views. Sometimes seeing the code can help understand how the view works in case it needs further tweaking.
You can change the settings for the access to the database that are contained in the settings.php file used by your Drupal site to something similar to the following one (replace the values between brackets with the correct values for your site):
Solr is a standalone enterprise search server with a REST-like API. You put documents in it (called "indexing") via XML, JSON, CSV or binary over HTTP. You query it via HTTP GET and receive XML, JSON, CSV or binary results.
CPU Bound means the rate at which process progresses is limited by the speed of the CPU. A task that performs calculations on a small set of numbers, for example multiplying small matrices, is likely to be CPU bound.