How to take apart a film pack to use as single sheets

I've been using xray film in 3 1/4 x 4 1/4 plate holders - I put a piece of plexiglass in the holder to act as the glass plate and lay the film on top so it is nice and flat. But now I just got an old PLUS-X 518 film pack (3 1/4 x 4 1/4). I want to be prepared when I separate the unexposed film sheets from the pack -

1) is this really the same size as normal sheet film?
2) is the film "stuck" to the paper somehow?
3) does the film have the typical top-right notch or will I have to be careful to keep track of which side the emulsion is on?
4) Expired in 1955. 1st shot will be an in-camera test strip using dark slide. But do I really need to use HC110 or can I use rodinal? I don't have benzo but I have many other developer ingredients I can to the add rodinal if needed.

In addition, something to know is the thickness. I helical pack films are much thinner than sheet film.

It's completely different from regular sheet film. It's longer, and very flimsy. I've never used Xray film but I've used 4x5 pack film. It's great because you can shoot a few sheets, then go to the darkroom and pull the exposed sheets and develop. The film is taped to the paper. In use the paper is pulled out to advance the film to the front, then the paper is torn off, what remains on the film is tape and maybe a bit of paper, it's been about 30 years since I used pack film.
I don't remember about the notches.the film won't fit a normal holder or a normal film hanger.
It's absolutely age fogged, but it doesn't hurt to try. Halides will act as a restrainer if you don't have anti-fog, potassium bromide, or even table salt. I would use whatever developer you have without any additives and normal development time for first sheet, the test strip is an excellent idea.
Everyone used to make pack film in the 40's. Very nice for press and event photographers. Each company had slightly different dimensions.

To use single sheets make the exposures, then in the darkroom open the pack by sliding the small (about 1"wide) piece of metal off. Separate the front and back just enough to remove the used films then replace the sliding metal lock on the pack. Ready to again.
I add KBr to the developer to assist in reducing age fog.

I have a couple NOS film packs that old but never tried using, I am aging then a bit more...

I have touched the very thin film that is way thinner than 'normal' films

I have shot NOS Glass plates that were older, perhaps 1920's

Some say use an extra stop per decade with old emusions

So try 4 stops more light for a start

Tray process one at a time in complete darkness

I use Rodinol for almost every film, sometimes Ilford PQ 1/19 as it works in 5 minutes

Post whatever shows up here

Please!

and in other threads similar

oops forgot to add, my hat avatar was shot on ancient 5X7 glass plate

so make each shot count

Here is the instruction sheet from a Kodak Film Pack. It is not difficult to remove or "rob" a sheet of film from the pack. One caution though is to be very careful of the sharp edges of the metal film pack itself.Attachment 199683

Thank you all for your help and information. The filmpack sheets do fit in the plate holder and although I had to cut the paper edge off in the darkbag, I would just refrain from pulling the dark slide all the way out. Unfortunately the film was fogged too much, I started by developing 1/2 a sheet unexposed to light and it was quite disappointing. I exposed a sheet at about 3x stops and could not make out a single thing. At least I now understand film packs and for 10 bucks I have a nice original package to show off on my display shelf amongst my cameras.