Yes, this sort-of answers my questions. However, my mind boggles at the nature of some of the conversations they must have had.

] ] How were such settlements or fortunes advertised?

] Mercenary lot, were they not? It does seem apparent that when a young lady was avaiable for marriage, her financial status was usually spread about, as bait for those who were interested. Servants seem to have been pretty instrumental in this. Public gossip also played its part. However, it was all speculative.

So one made sure to discuss one's financial affairs in front of the servants, and they understood that they were to spread it as gossip to the servants of other families?

"James, if you would be so good as to rearange the pillows? So, my dear Jane, in addition to the 5000 pounds I have for you in 5% bonds, I'll also sell Fotheringsque Abbey to raise a further 5000 pounds for you when you marry. Thank will be all, thank you James - you can take the rest of the day off."

] ] how can he assure himself of the truth of this, prior to becoming engaged?

] That was why he applied to the father for her hand in marriage, not to the the girl herself. That was the first step in serious discussion and truth-telling.

] ] it would seem to be very much to the advantage of a lady with three thousand pounds to have it generally believed that she had ten thousand.

] You bet it did. It was up to the suitor to investigate the truth of such statements. But don't forget that an engagement was a formal affair, and wouldn't be announced until all parties were satisfied as to such details. There couild be a period of negotiations between the father and the suitor.

It could still be of benefit to the lady to set inflated expectations. A gentleman may be predisposed to think well of a lady with ten thousand pounds, and to court her. By the time he has reached the point of applying to her father, he may be sufficiently in love to take her despite her true wealth, but had he known at the outset, he would never have started courting.

In JA novels, I think that the gentleman more often proposes first and seeks parental permission afterwards, rather than the converse. This could lead to awkward situations when he is mistaken about her wealth:

Scene 1: A garden.
William: I love you more than life itself! Wealth is of no consequence for a love such as ours! Will you be my bride?
Margaret: Yeah, sure thing.
William: I shall apply to your father directly!

Scene 2: A study
William: I wish to ask your permission for your daughter Margaret's hand in marriage.
Sir Charles: Gladly! I will settle three thousand pounds on her.
William: Three?! Sod that. I hear Mary King's worth ten. I'm out of here.

Scene 3: A drawing room
William: Alas, my love, it cannot be - your father has refused his permission. Remember me with tenderness - we shall never meet again.
(He exits, as if persued by a bear.)
(Enter Sir Charles.)
Sir Charles: He wanted ten thousand pounds.
Margaret: Drat. Time to pull off a bank job.

] ] There are aspects of all this in Northanger Abbey, where the Moreland family's fortune is variously mis-estimated.

] Actually, in all of the books, the relative wealth of the heroine(s)is a major factor in the story.

But only in NA does the accuracy of people's estimates of this wealth become an issue. In all the others, everyone who needs to know seems to have correct information.

] ] For that matter, how is it that everyone is so knowlegable about the fortunes of the young men?

] ... Sometimes financial status would be noted in almanacs, newspapers etc, also, just as it is today.

Ah, like the annual "rich list" that one of the business papers in my country produces.