and if they want a true-up, it's easy enough to code software to do it on a recurring basis every week using "year-to-date minus prior" or your system's equivalent language.
No, not unless the document says otherwise.
Yes
Yes
Agree, terminated participants are not eligible for the match and/or true up if they have a last day allocation condition. Be sure to check the document as it may provide an exception to the allocation conditions for termination due to death, disability or retirement. A pay period match with a last day rule is a poorly designed plan.
The 1096 is used by the government to verify the taxes withheld for the YEAR as well as the amounts paid. If you use a 2021 1096, the IRS will look for the amounts in 2021. How many letters are you willing to write to explain the discrepancy??