How to edit DNG in Photoshop after adjustments but without them?

Question

Ok, this might seem a stupid question but let me properly explain...
Just to make it clear, I now know I cannot edit a DNG directly in Photoshop, this must be converted to TIFF and that one can be edited and imported back into Lightroom.
I've read many posts where people tend to all LR adjustments and then go to PS for the final touches, but I prefer the other way around, PS first for any pixel editing and LR to finish the image. But I have two problems this simply because I forgot to edit some image in PS before making my LR adjustments. The only thing I wanted to do in PS was to remove some sensor dust I didn't notice before.
The problem is that I have now finished all my LR adjustments and I can't find a proper way to edit the original (without LR adjustments). When I open the context menu in LR and select Edit » Photoshop, all LR adjustments will be processed and the TIFF file generated will have them.
Q1: Isn't there a way to edit a DNG file in Photoshop without LR adjustments just like we can do it for any other type of file that is not some sort of RAW file?
To answer my own question, the only way I found to do this was to preset the Reset button in the Develop module in LR and then to Edit » Photoshop. This will work but it's a little bit clumsy, anyway to avoid this or is it my only option?
Let's say I do it like that anyway. I'm now with the original untouched DNG file converted to TIFF opened in Photoshop, I do all my pixel editing and save the file. This TIFF file will be automatically imported into Lightroom so I can do any final touches. Since I did a "reset" and the image edited in Photoshop was the original untouched by LR, I now need to do all my editing in LR all over again.
I though of simply copying all develop settings from the old original DNG into the new converted TIFF. But this doesn't work, the files are different, the same settings do not work for these 2 different fle types. The image looks completetly different.
Q2: How can I fix this without playing with all the sliders again to achieve the same look?
I've been done this road before and it was a painful process, in the end, I was not able to get the same exact result.
EDIT: I did not mention the spot removal tool because I wasn't getting very good results with it, it doesn't work as good as Photoshop's tools. The sensor dust was in the sky and very close to some clouds, selecting the whole thing was not working. After some time, I added 5 spot removals and was able to properly clean the sky of that dust. Still would love to hear opinions on my questions above.

Answer 1

Not it's not, it's my workflow, why don't you understand that? If I want to edit in PS first, well, that's my decision, you are assuming I want to keep the RAW data intact and if I wanted yes, my workflow would be wrong because I couldn't do it like that, but I don't want to keep it. Actually, in a perfect world, I would want to be able to keep RAW data and do som pixel editing in the same file, but this is not a perfect world so I'm fine in losing the RAW data. I never stated that but I though it was implicit the way I described my workflow.
I already knew everything you said in your post, nothing new there.
"You really can't move back and forth it one direction only..."
Like I said, I'm not looking moving back and forth, I don't think yous guys are understanding my question properly. Let's take another approach to see if you guys understand it better. I shot some photo in RAW and converted it to JPG (yes JPG), I've now lost any RAW data. However, I like to keep my files in DNG (DNG is a container so I can do that) and convert the JPG file into a DNG. I know have my "master" file as a JPG file in a DNG container.
I start to do some editing in LR in my master file but I forgot to remove the dust on Photoshop and now I need someway to open the original in Photoshop to remove it, because I don't want to lose all my LR adjustments, I want to edit the original and keep my LR adjustments. But even if the file inside the DNG container is a JPG file, since the file format is DNG, I don't have the option to Edit without LR adjustments when I chose Edit » Photoshop. As soon as I do that, the DNG file will be opened in PS with all LR adjustments, but this file is actually a JPG, there's no RAW data anymore. The only way to edit the original file like this is to "reset" all LR adjustments before going pressing the edit context menu option and then copy back all settings from a to b.
Now, this will work just fine because the original file is no longer RAW data, but linear data (I think it's called like this? what I mean, is a JPG, not RAW; i'll call it like this from now on, sorry if this is wrong) and so the settings can be copied at will from one file to ther other without any problems. After a bit of research I read around this forums that LR settings differ slightly if the original file is RAW data or linear data. For instance, the middle point for Temperature is actually 0 for JPG files but if it's a RAW file, it's something like 6500K (not necessarily this, just an example), and that means I can't copy the settings back and forth with a copy/paste.
So, to recapitulate...
My original image is now linear data (JPG) not RAW and saved into a DNG container and since it's a DNG container I cannot open the context menu Edit » Photoshop » Without LR Adjustments. Why? Is there any other any way around it or there's nothing I can besides making a reset or saving a snapshot in LR with the original settings so I can open them at will in PS and then copy the settings from a to b. I just don't understand why there isn't an option, for DNG files, to open it without all LR adjustments like all other files. It's actually a JPG file inside, not RAW data, so, why not? But even if it was RAW data, there could be such an option to. I mean, when you have RAW data and press Edit » Photoshop, the file will be demosaiced (or whatever it's called) and opened in PS, when you save it, it will be saved as TIFF. So why isn't there an option to demosaic the original file without LR adjustments.
As to my second question, I guess there's no way to solve it either. The data on each file is different and the sliders behave differently so there's not way to copy the settings from a file to another if the saved data is not of the same type. And there's also no way to "convert" the settings from one file to the other, or is there? That was actually my question, if there was a way to copy/convert the settings from a RAW file into a linear file so I don't have to move all the sliders all over again and try to achieve the same goal. But after a quick search around the forums, I found a related question and I guess there's no way to do it.