The analyses of a text #4

The narrator recalls his childhood.
He was forced to work for his own living for Mr. Murdstone's friend Mr. Quinion at London by his stepfather Mr. Murdstone.
He lodges at a house, the master of which Mr. Micawber is so very poor, and goes to his work Murdstone and Grinby's.
At last Mr. Micawber was imprisoned in the King's Bench Prison for his dept.
He is to be released from the prison and the protagonist asks about Mrs. Micawber about future plans.

"My family," said Mrs. Micawber, who always said those two words with an air, though I never could discover who came under the denomination, "my family are of opinion that Mr. Micawber should quit London, and exert his talents in the country. Mr. Micawber is a great talent, Master Copperfield."
I said I was sure of that.
"Of great talent," repeated Mrs. Micawber. "My family are of opinion, that, with a little interest, something might be done for a man his ability in the Custom House. The influence of my family being local, it is their wish that Mr. Micawber should go down to Plymouth. They think it indispensable that he should be upon the spot."
"That he may be ready?" I suggested.
"Exactly," returned Mrs. Micawber. "That he may be ready?in case of anything turning up."
[David Copperfield by Charles Dickens]
I'd like to know what part or parts "of great talent" modifies.
And I'd like to know what role two "that"s play.
Thank you in advance for your help.