1- Put semi-decent spies in your cities and army stacks. No assassains.
2- Releasing gives you points. Ransoming doesn't take points away.
3- Not sure, I'll defer to someone who understands how BattleChivalry works.
4- I've had v. high taxes on in all my cities and still gotten chivalry points. I think that you just need to keep the city's PO above 100 and you'll pick up chivalry points, but I'm not certain.
5- Improves morale of your troops in battle (as opposed to taking away the enemy's, like dread does) and it increases the population growth rate in cities, which may in turn increase PO if you've got enough growth. Don't think it gives anything else to PO.
6- These things have more to do with your diplomatic reputation than your chivalry.
7- I've been trying things this way in a couple of campaigns. I like it mainly because I don't have to micromanage assassains on top of all the other agents. Send a couple of generals on crusade whenever you can, and you should be able to get the chivalrous father snowball going. That, and watching your taxes, should get you the high chivalry generals you want.