I have had to edit down your original question because it infringed enotes policy by asking more than one question. I have therefore edited your question to focus on the presentation of the aristocracy more generally.
It is clear that in this novel Dickens goes through great strengths to present the French Aristocracy in an unfavourable light. Even if we ignore obvious caricatures of the evil French aristocracy such as the Marquis of Evremonde, there are still highly amusing scenes exposing their vanity. Consider Chapter 7 in Book II, when we are presented to Monseigneur:
Monseigneur was in his inner room, his sanctuary of sanctuaries, the Holiest of Holiests to the crowd of worshippers in the suite of rooms without. Monseigneur was about to take his chocolate. Monseigneur could swallow a great many things with ease, and was by some few sullen minds supposed to be rather rapidly swallowing France; but, his morning's chocolate could not so much as get into the throat of Monseigneur, without the aid of four strong men besides the Cook.
This passage is clearly dripping with irony - note the ironic religious allusion to the "Holiest of Holiests", clearly indicating the absurdly high prestige and position in society that Monseigneur had. Also note the "few sullen minds" that comment how Monseigneur is in danger of swallowing France - reducing it to a state of absolute poverty while he drinks deep. The absurdity of the necessity for four strong men to convey Monseigneur's chocolate is likewise highlighted.
Dickens is clear is his judgement of the aristocracy, and in the following chapter there are far harsher examples emerging from the Marquis for you to focus on. Yet at the same time it is important to realise that Dickens equally does not condone the violent results of the Revolution. Chapter 2 in Book III for example, "The Grindstone", is one of the most hideous and disturbing passages in the whole story, as it describes the slaughter of unarmed prisoners by a violent mob, rejoicing in its berserk state. Therefore you could argue that the aristocracy get what they deserve to a certain extent - they were guilty of impoverishing France at large; but Dickens is clear that the violent methods employed by the Revolution were just as unacceptable as the Aristocracy themselves.