My choice for "most natural-sounding option" is A-6, with the additional modification that "It has" would be contracted to "It's":
It's been a year now since you promised me (something).
This formulation focuses more on the passage of time; we are emphasizing that a long time has come and gone since the promise was issued. (It does not need to be exactly one year, you could reasonably say it any time from 11 1/2 months to 18 months after the date the promise was issued, although some people might nitpick at your accuracy.)
The first 4 options in set A ("it is a/one year now that/since you promised me") all use the present tense, which cannot work when speaking of something that happened in the past; option 5's use of "one" instead of "a" breaks the natural stress that should fall on "year".
Set B's choices emphasize our arrival at the anniversary date of the promise, which to me seems less likely to be the thing that we want to emphasize; within that set, however, option 2 is clearly the best choice, because using "a" instead of "one" lets the stress fall naturally on the word "year", where it belongs; and because options 3 and 4 have no referent for the pronoun "this", making them improper.
We would say, "how long have you lived there?" (present perfect; began in the past and continues)
Or, "how long has your family lived there?"
We might say "How many years have you lived here?" if the precise number of years were critically important, e.g., you are eligible for some benefit after living in a place for three years. But usually "how long" is the better option.
Best Answer
When discussing centuries, as in Norwegians came to the New World in the eleventh century, you may have to resort to some old fashioned sounding sentences. I would say Hrvald the Norwegian sailed the ocean in the ninety second year of the eleventh century (1092), or if you want to get really uncommon, ... sailed the ocean in the ninety second year of the second millennium.