How we cite our quotes: (Act.Scene.Line)
Quote #4
[…] places in the court are but like beds in the hospital,
where this man's head lies at that man's foot, and so lower,
and lower. (1.1.65-67)
Bosola is once again (surprise, surprise!) complaining about the court. Here, he's deploring the vicious cycle courtiers get stuck in as they scrabble over each others' backs for the prince's favor. Bosola describes the system of courtly advancement in terms that carry the same tone as his crooked trees metaphor from Quote #2, in that he's presenting us with a picture of social rot, instead of generation or health.
Quote #5
Where he is jealous of any man he lays worse plots
for them than ever was imposed on Hercules, for he strews
in his way flatterers, panders, intelligencers, atheists, and a
thousand such political monsters. (1.1.155-58)
Antonio is painting a not-too-flattering portrait of the Cardinal for his friends Delio. He's a terrible guy in general, but in particular he's the Terrible Guy version of a politician—he surrounds himself with "political monsters," a bunch of useful but totally disposable people the Cardinal can use to boost his own power. In the Cardinal, you see the decay of Christian values in all of its ugly glory. He has absolutely no sense of ethics, and his position within the church is simply another platform from which he can amass power.
Quote #6
For know: an honest statesman to a prince
Is like a cedar planted by a spring;
The spring bathes the tree's root, the grateful tree
Rewards it with his shadow. You have not done so.
I would sooner swim to the Bermoothes
[…]
Than depend on so changeable a prince's favour! (3.2.258-65)
Bosola is criticizing the Duchess for axing Antonio, telling her how a court should work. Contrast this with the tree-pool metaphor he uses in Quote 3 to describe the perverse rule of the Cardinal and Ferdinand. In these later lines, Bosola rewrites the tree-spool image to describe something much closer to the French king's system, whereby ruler and ruled are nourished by each other and flourish.