10-12 episodes per season, 40-45 minutes per episode for dramatic shows and 20-25 minutes for cartoons/comedy, I'd be okay with the occasional longer episode if it's justified but I don't want longer episodes just because they can be longer.
I prefer the episodes to start with the title sequence, no teaser. The only point of a teaser is to hook the audience fast and stopping them from switching the channel after whatever came before, that's not an issue with streaming, when people hit play they've already decided to watch.
I really enjoyed the short treks and hope they continue that format too. It's perfect for more out there ideas or to revisit characters or places we've seen before but they don't fit into the current seasons anymore.
Shows like DSC are still broadcast in places like Canada. In the US, they are broadcasting S1 on CBS right now.