Is there any situation where the ci here could have been for emphasis and not meaning "us" - like, "My sister buys this here cake" approximately in English? Just trying to get this "pronoun vs. emphasis" idea down...
A noi = ci. In general that is the role of the indirect object pronouns: a me = mi, a te = ti, a lui = gli, a lei = le, a noi = ci, a voi = vi, a loro = loro. Their placement just infront of the verb is crucial syntactically.
Hmmm. Did you write 'Lui ci legge un giornale'? That is correct. On the other hand, if you wrote 'Lui leggi ci un giornale', that is incorrect word order: clitic pronouns appear immediately before the conjugated verb.
This one could be even trickier, since "ci" could also mean "with it".and put an emphasis on the means of the action.
E.g. "Con tutti quei soldi, mia sorella ci compra una torta".
(="With all that money, my sister buys [even better, could buy] a cake")
I believe "ci" changes to "ce" when followed by an object "clitic". Same for "me", "ti", "si", and "ve". I thnk they covered this in the Tips at the start of the lesson. I certainly could be wrong--I'm having a tough time with this lesson too.