The analyses of a text #1

The narrator recalls his adolescence.
He was an apprentice for Mr. Spenlow.
He and Mr. Spenlow's only daughter Dora fell in love with each other, but after Mr. Spenlow's sudden death, she moved in with her two aunts and confined herself there.
He made an appointment with Dora's aunts to visit them through correspondence and came Dora's aunts' house with his best friend Traddles.
Miss Lavinia and Clarissa are Dora's aunts; Miss Lavinia, the younger one took the lead in this conversation.

..............
Miss Lavinia proceeded:
'Mr. Copperfield, my sister Clarissa and I have been very careful indeed in considering this letter; and we have not considered it without finally showing it to our niece, and discussing it with our niece. We have no doubt that you think you like her very much.'
'Think, ma'am,' I rapturously began, 'oh! -'
But Miss Clarissa giving me a look (just like a sharp canary), as requesting that I would not interrupt the oracle, I begged pardon.
'Affection,' said Miss Lavinia, glancing at her sister for corroboration, which she gave in the form of a little nod to every clause, 'mature affection, homage, devotion, does not easily express itself. Its voice is low. It is modest and retiring, it lies in ambush, waits and waits. Such is the mature fruit. Sometimes a life glides away, and finds it still ripening in the shade.'
Of course I did not understand then that this was an allusion to her supposed experience of the stricken Pidger; but I saw, from the gravity with which Miss Clarissa nodded her head, that great weight was attached to these words.
'The light - for I call them, in comparison with such sentiments, the light - inclinations of very young people,' pursued Miss Lavinia, 'are dust, compared to rocks. It is owing to the difficulty of knowing whether they are likely to endure or have any real foundation, that my sister Clarissa and myself have been very undecided how to act, Mr. Copperfield, and Mr. -'
'Traddles,' said my friend, finding himself looked at.
[David Copperfield by Charles Dickens]
1. I'd like to know what "for" means here.
2. I'd like to know if "the light inclinations" is the objective complement of "call."
3. And I'd like to know if "so" is implied before "that."
Thank you in advance for your help.