Questions concerning additional accounts

I have a 'small storage' hybrid 2-in-1 tablet PC. In addition to my main (Administrator) account I have two additional accounts, to which I have given very little attention until now. One was created by a MS tech to help with some remote work he did; one (local Administrator) was created by me by clicking a menu item in Winaero Tweaker. I am giving them some attention at the moment as a part of preparing for the immanent October update, which is the reason for question 1, as follows:

1. what effect do these extra accounts have on available storage space on my C drive? If I were to remove one or both of them would this release some storage space on my small emmc SSD C drive? Would it be an insignificant amount (lets say less than 1 GB) or might it make a worthwhile difference?

2. what determines what is displayed when I open these accounts, they do not have the desktop from my main account, instead they have a 'selection' of the main account's desktop icons which is different in each case. How is this 'selection' made? It looks somewhat random.

3. as I am the only user are there useful things which can be achieved with these additional accounts? So far I have not even created any extra desktops in my main account, though I can see this is something I may do at some point.

I hope this makes sense!

Thanks, your response has been very helpful. Using Tree Size I seem to have maybe 2 or 4 GB tied up in the Christopher account, either of which would be worthwhile to release. (The other account is much smaller an anyway is Administrator so better left alone).
I would appreciate some guidance regarding removal to be sure I am doing the right thing. The reason I have said 2GB or 4GB is that the 2GB is listed as 'allocated' which I am not clear about. Is it the same as what I would call 'in use' or 'occupied', and the other 2GB is 'vacant' or 'available', ie. 'unused'. If I have got this right, I presume I could release some / all of the 'in use' storage by simply deleting the C drive files I have found in File Explorer? Or, if I delete the Christopher folder I guess I would release the 4GB, and at the same time I would have removed the Christopher account itself? 2GB would be worthwhile, 4GB even better.
In addition, if I have understood this correctly, I am wondering how the 4GB total came to be created in the first place as I would expect space to only have been created as and when it is used, ie. allocated, instead of both used and unused.. Otherwise why 4GB and not some other figure.

Steep learning curve detected!