Get name of table for a field
What you need to use is the fieldCondition
, which works pretty much like entityCondition and propertyCondition, only you are adding a condition for the field and not the entity or one of it's properties.

This is how you should query fields and entities.

If you wanted to get info about the how the data of a field was stored, that information is available on the field itself. So you could do

$field = field_info_field('field_name');
$storage_details = $field['storage']['details'];


What info you get depends on how the field is stored, as Drupal support multiple storage backends for fields.