The Bramleighs of Bishop's Folly

Hi

desultory
adjective
1. lacking in consistency, constancy, or visible order, disconnected; fitful:
desultory conversation.
2. digressing from or unconnected with the main subject; random:
a desultory remark.

"It strikes me," said Marion, rising, "that this sort of desultory conversation on a matter of such importance is, to say the least, inconvenient…"
Charles Lever, The Bramleighs of Bishop's Folly, 1868

This introduction of a comprehensive purpose in gathering contributions that otherwise might be disconnected and desultory is an idea well worth transplanting wherever admissible.
George Iles, "Success with Scientific and Other Meetings," The Popular Science Monthly, August, 1893

constancy
noun
1. the quality of being unchanging or unwavering, as in purpose, love, or loyalty; firmness of mind; faithfulness.
2. uniformity or regularity, as in qualities or conditions; invariableness.

consistency
noun
1. a degree of density, firmness, viscosity, etc.:
The liquid has the consistency of cream.
2. steadfast adherence to the same principles, course, form, etc.:
There is consistency in his pattern of behavior.

[All definitions taken from Dictionary.com]

Could you please help me with the queries below? Thank you.

Q1:
I'm just curious to know that what 'Bramleighs' means in the title "The Bramleighs of Bishop's Folly". If someone of you has read it then you would be able to help me with it.

Q2:
How would you define 'comprehensive purpose'?

Q3:
I believe that there is a lot of overlap between definition #1 of 'constancy' and definition #2 of 'consistency' and in such cases replacing 'consistency' with 'constancy' wouldn't alter the overall meaning. For example, the sentence 'There is consistency/constancy in his pattern of behavior' mean the same with both words.