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It is hard to answer with 100% confidence. The text does not specify it explicitly.
However, I would guess, Marina saw her Grandmother before, maybe for some short period of time. The key word here...

1-3 are OK.
4: а = "in contrast to": "А я ..." = "And as to me, I ..."

6: approximately "ты знаешь" and "ведь" mean the same in this context. But they can be even combined:
Ты знаешь, я ведь...