The second person imperative always implies the subject (at least since we stopped saying thee, and even then the subject and verb were inverted, as it remains in the first person plural imperative). The first sentence in the second example is a complete sentence; only the second is a fragment.
If you see an imperative "get" with an apparent subject, it's probably a topic rather than a subject:
"Paul, get your boots on and get going!"
You are speaking to Paul:
"Get your boots on and get going!"
You use the topic to designate or call attention; it's not the subject of the sentence.
If you see an imperative "get" with an apparent subject, it's probably a topic rather than a subject:
"Paul, get your boots on and get going!"
You are speaking to Paul:
"Get your boots on and get going!"
You use the topic to designate or call attention; it's not the subject of the sentence.