I have reported a Rest api write functionality bug, which is always repeatable with demo data.

>1) How can we fetch or get only updated data after a specific time interval?

I would use updates_after and/or RegDate field in some registers (TRVc) to fetch only new records. I have a note: if we specify "updates_after=0", "offset" does not work - records are fetched from the first one. This could be fixed at this time, don't remember which exact version I have tested it with.