Miss Hawkins's dowry is of ten thousand pounds, but this is because she is an orphan living with her uncle. Therefore she can expect nothing more in the future — her uncle being probably a mere clerk.
As Emma is not an orphan (her father being alive), it is very probable that she has not yet the total of the thirty thousand pounds of which she is the heiress, but only of part of it, whether already, whether at her marriage.
As for Mr John Knightley, by "entitled" I meant exactly the sort of settlement you wrote, please excuse me if it was not the right word.
And regarding Donwell Abbey, it is well managed at the time of the novel, perhaps because Mr Knightley, with the help of William Larkin and with a set of good, or even excellent (as Robert Martin) farmers, have improved it, maybe along twenty years (I see him as a rather early orphan) at the point of making it an excellent estate, but not since a long time. Hence the money concerns for the two brothers, that have been in past, that are much less for present and not much to be feared for future (in the novel; as in the reality, the post-war crisis hit strongly Britain).