I tested all 4 of your issues in a vanilla test game with no mods and CC. I tested on 2 different lots. My game is fully updated, and I have all packs including the new one.
For items 1-3, with MOO on, those work just the way they always have for me. They did not do what you say they are doing for you. I was able to change wallpaper at will without deleting anything. I did notice that with MOO off, several things on the wall, in my case, a door and an over window upper cabinet, highlighted in yellow but the after changing the paint, they did remain in place. I had no problem whatsoever placing columns. Again, nothing got deleted. And I was able to place a tree and a mailbox with the footprint slightly off the lot with no problem. However, I don't recommend doing that if you are going to save the lot to your library or upload to the gallery as it is very likely that they will disappear when the lot is reinstalled. It does work if you play the lot where you built it. I've had items placed like that disappear on a few of the lots I've built when I reinstalled the lot. I did get the error message though if i tried to place the object with too much of the footprint off the lot. Again, that is normal.
For item 4. By default, whenever you exit one of the Eco Lifestyle multi lots directly from build when you go to build from the map, it will revert to the community space. To get the Market or other two lot types to stick, you have to do it by voting in live mode. It's always been that way.
So, it appears that something is off in your save or the game. I suggest another repair. I have found that sometimes, it might take doing a repair twice for it to stick so try doing another one. If that does not fix it, then I suggest you create a new user folder and move your save from the old folder to the new one. You might want to start a new save in the new folder first and check if the issues you have reported are present in the new save before opening your old one. There might be a problem with the save where you ran into these issues rather than with the game itself. A repair won't fix problems with a save, only the game files.
Hope this helps.
