In 2 level you mean a parent and children, you can do this in a single query, although it contains a subquery that counts as another SOQL query for governor ....
Please check the following for the difference between Profile and Permission Set in Salesforce. Profile: A profile contains user permissions and access settings that control what users can do within ....
Allows users to enter any combination of letters and numbers and store them in encrypted form. Encrypted fields are encrypted with 128-bit master keys and use the Advanced Encryption Standard ....
Whenever a user modifies any of the fields selected below, the old and new field values are added to the History related list as well as the date, time, nature ....
Lookup filter is used to filter the values to be shown in lookup relation. Check the below link for more details http://infallibletechie.blogspot.in/2013/04/lookup-filter-in-salesforce.html Cheers!!!
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