I think #1 is much more plausible. Notice that Draco did not misuse any terms, and addressed Quirrel twice as 'Professor'; saying 'Abracadabra' is flippant and a tad contemptuous of the greatest gem of Quirrel's chosen field.
The personal version seems to either trade on knowledge of canon (not the first time, though! and such references can be spotted on the first read-through) or presume a version of Voldemort's fall we currently have no evidence for, although this is certainly a controversial topic.
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1 sounds plausible because the name of the spell is also the manner in which it is cast; to develop the habit of saying a spell's name wrong could result in an accidental, disastrous misfire.
Option 3: Both.