Questions about what is fixed

So my questions are probably going to take some time to answer because people are only getting into the game today, but I'm going to put them here and hopefully get answers over time. 

First, I'm seeing a ton of bug reports. Did they fix anything? Shadows, various graphics file issues that we UC players have manually fixed in our games ourselves? Do we need to apply the 4gb patch anymore? Is the game actually running smoothly for anyone?

Second, did they fix any of the corruption they left in the game the first time around? Missing memories, missing Sims? Broken memory links? Missing tombstones? The incorrect path that made Gamesend Grounds not work as a cemetery without a mod? 

That second one is a big one for me. I literally spent a year cleaning up my neighborhoods. Replacing corrupted memories, restoring information that was missing from ancestors, restoring and placing tombstones. Replacing ancestors when their files were too corrupt. If they didn't fix any of these things, then am I able to move my cleaned neighborhoods into this new game? If I can't, is it even possible to do it again? (I admit some of this is SimPe related and that's no longer updated, so the answer is probably no.)

Third, someone on Reddit has reported that the IKEA pack files can be copied from UC into the Legacy folders and it works fine. This person is using Steam however, so what I need to know is will this work with the EA app? Someone with UC needs to test it!

Please, please, people find some of these answers for me! I have been begging for a re-release for a decade and I want to know if it's worth buying.