But you will have to rebuild the stairs. You can't have stair risers that vary like that--it's code. They must all be the same height, to within less than 3/8".

Too expensive to change it so I would learn to live with it. Maybe use a nice tile riser and a wooden bullnose stair edge that shows you actually like the step and have embraced it? Right now it looks poorly finished.

This requires all of the items mentioned above plus all the window will now need to tempered glass since they will be too close to the floor. I would be curious to know what is under the raised floor in the entry and the kitchen. I would for sure want to eliminate the raised entry if possible since it is small and IMO an accident waiting to happen. IMO it would be cheaper to lower those floors than raise the LR one if there is nothing going on in them. ince you are doing the kitchen anyway .

You'll be dealing one way or another with the length of the wall you remove. I can't see that being one long step down.