Let me try answer you in detail (and with specific examples) to these questions.....
I wonder, does anyone have experience with, or has anyone done an experiment on how difficult it is to walk around a km or more in deep snow with only socks on your feet?
There is of course. Here is link to the video of this event: https://youtu.be/FAuxkkISqmI?list=PLQUaBB5B8ds5kQyCbh9oBIHKApv9_CT72
And then it was done twice - the second time, one day later, at night. I do not give reference to it only because there is almost no visibility. This was unsuccessful attempt get at least something when shooting at night.
This depends on the type of snow, but there is mention in the diaries of snow "being blown by the wind, probably from trees because the sky is blue", and also on the photo where they're setting up the tent, clearly there is snow on their clothes, so I assume the snow was the loose kind...
It was a story about what they saw elsewhere. There are different conditions in different places. You yourself bring a few photos:
1 - https://dyatlovpass.com/resources/340/gallery/Dyatlov-pass-1959-search-017.jpg
2 - https://dyatlovpass.com/resources/340/gallery/Dyatlov-pass-1959-search-017.jpg
3 - https://dyatlovpass.com/resources/340/gallery/Dyatlov-pass-1959-search-000.jpg
They are also made in different places if you go down a slope in the order of numbers: 3 - 1 - 2. I just want remind you that photo #2 was taken at the end of March, when the snow fell already lot.
On the video, where Shura Alexeyenkov walks in socks of snow was also much more than it was in 1959.
Also based on the same photo, it was at least a metre deep around the tent.
Near the tent there was different amount of snow from different sides, but there was hard snow (this is called nast - thin crust of ice over snow) so the depth of snow did not matter. I have to explain that the shots https://dyatlovpass.com/resources/340/thumbs/Unknown-origin-Dyatlov-photos-11.jpg
are not made in the place where the tent was, these are completely different conditions and snow conditions. This photo does not have exact reference points, both in time and place. According to all conditions, I assume that it was made on January 31, when they went to the top of the pass and unsuccessfully tried to make warehouse there.
When you step into deep, powdery snow, your feet sink into it, so I think it would be almost impossible to walk any considerable distance, this is why people use skis.
I know footprints were found in a part of the assumed route (between the tent and where the bodies were found), but I wonder if it's correct to assume that they walked the whole way..
You think it's right. But here we also need to make explanation: they could walk on parts of the slope without skis and they got to the place where it was possible. They could not go any further. The border of this can be seen on this diagram: https://dyatlovpass.com/resources/340/Dyatlov-pass-ravine-map-Borzenkov_1.png
If they could go further into the forest, they would stay alive, because they could make a big and good fire. In the place where they were found, there was no proper amount and condition of firewood.
The traces they had were not very small. Above their beginning, there were no conditions for their formation, but below their end, the tracks were covered with snow that blew out from above and they could not be seen.
They went all the way and there is no need doubt it, because the teleportation had not yet been invented even now.
You can see for yourself the same conditions somewhere in the north of your country, for example in Lappi - very good example is the Inari community. I know this because it borders on our Murmansk region, where I have been many times. The conditions are the same there. The difference with the Northern Urals will be such that the whole difference in snow conditions will be much shorter and faster.