Great post. I love seeing devs keep active in these difficult times. Here are some of my thoughts.

Bid bots:
Make any post upvoted to trending with a bid bot a different color than other posts. Or make posts that are "naturally trending" a different color.

Should Witness votes be permanent?
No. Decay is a good idea. Reminders that your votes decay is also a good idea.

Do you think it should remain 30 witness votes?
I like the "a vote for 15 is a bigger vote for them" idea.

Do you think 20/21 top witnesses a good number?
More top witnesses increases the perception of decentralization, and maybe actual decentralization. Either way it's a good idea, considering all the complaints I've seen about that.

Too much dependence on the rewards pool. Yes. Steem should be advertised as a place to earn perks, not get rich. Only problem is that some people actually do earn a lot, which creates jealousy and rage quitting. Reminding users that not everyone needs to be a professional blogger and can earn perks by leaving thoughtful comments might help.

MARKETING: If users can get extra perks based on the number of views they get coming from outside the Steem ecosystem, and people outside can easily see this, it might attract some of those people to join.