I have 3 packs, one with an expiry date of Oct23 and the other two Dec23, hence less than a year out of date, so hopefully will still give reasonably reliable results, though I’d advise getting a new pack if you need to be sure.
One pack of 7 tests per respondent, unless you have a convincing reason for needing 2 or 3 packs, or unless I have less than 3 replies.
(NB I will give you my full address only after agreeing a firm pick-up time. I find this necessary in order to discourage no-shows.)