1. The store is far away from here.

2. The store is far off from here.

3. The store is a long way away from here.

4. The store is a long way off from here.
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Are they all grammatical?
Far is used in a negative sentence and in a question. A long way is used in a positive sentence, the English Usage says. In this case, when far is used with 'off' or 'away,' can we use them in a positive sentence? No problem?

All are grammatically correct, and all are used just fine! No problem.