Hi,
I think the words 'in the mean time" and "finally" are conjunctive adverbs and can be said to be sentence adverbs, (I think) meaning they modify the whole sentences/clauses.
I have trouble if any of these conjucntive adverbs comes after the conjunction "and" in that I am not sure whether I need to put a comma (or commas) or not.
Have seen these bits from the Google Book search:
... and, in the meantime, the mortgagor bacame ...
... and, in the meantime, honoured me with his own remarks, ...
... and in the meantime you will be
..., andin the meantime, applied part of the rents and profits ...