Yes, negotiations with Weaver were going on and on, threatening the project and production schedule, so Cameron spread the word that he intended to rewrite the script without the Ripley character, with this word getting back to Weaver's agent. Weaver signed shortly thereafter.
Probably because until the new AI processes became available, if that's what was used, the technology didn't exist to get the films into a version that suited Cameron without taking up a lot of his time and a lot of studio money (probably more than they wanted to pay for catalog releases). The...
I've always had a soft spot for Alien 3, as that's the first one I saw in theaters. Love the xenomorph design and FX in Resurrection (the regular versions, not the "hybrid"). Didn't care much for the rest of the film.