The analyses of a text

Besides which, all that I could have said of the Story, to any purpose, I had endeavoured to say in it.

It would concern the reader little, perhaps, to know how sorrowfully the pen is laid down at the close of a two years' imaginative task; or how an Author feels as if he were dismissing some portion of himself into the shadowy world, when a crowd of the creatures of his brain are going from him for ever. Yet, I had nothing else to tell; unless, indeed, I were to confess (which might be of less moment still), that no one can ever believe this Narrative, in the reading, more than I believed it in the writing.

[The preface in David Copperfield by Charles Dickens]

I'd like to know if "to know" means "to let you know."

I'd like to know what "of less moment still" means here.

Thank you in advance for your help.