No, it adds no extra flavor, or meaning to one sentence.
The word 'of' is a PREPESITION.
Yes, "at" is a preposition that typically indicates location or position. It is used to show the position of something or someone in relation to a specific place or object.
A preposition is a word that shows the relationship between a noun (or pronoun) and other words in a sentence. Prepositions often indicate location, direction, time, or the relationship between two things. Example prepositions include "in," "on," "under," "over," and "between."