Jeff*H
Premium
I don't think they started running the episode promos at the beginning of the shows until season 9 (these were also shown in syndication starting then). They did run the promos as 'next week's scenes' prior to the end credits most weeks.
The episodes were still slightly longer than 50 minutes (R1) in season 5 if I recall. By season 9 or 10, they were coming in around 49:30. In season 1 they were around 51:00.
And yes, in season 5 the 'cold opens' were moved to immediately after the main title sequence. They would run several minutes, then the episode's title and credits would appear as the story continued. I think by season 6 or 7, most episodes had their credits immediately following the main title sequence.