I will attempt to answer some of your questions.
I didn't see factory roll crimps in your photo. I have one empty vintage brass case with a big roll crimp, I haven't a clue how to remove it.
Annealing is a good precaution for case life. That said I haven't had any split cases, but my loads are very mild.
Supplies:
I use Large Pistol Primers, I don't believe Magnum Primers are necessary. The consensus on Magnum Primers for BPCR is they should not be used for numerous negative reasons. Perhaps in subzero temperatures?
For 12 Gauge:
Circle Fly brand Wads:
11 Gauge 1/8" Nitro Cards. However they are not a tight fit and "perhaps" using 10 Gauge would be a better fit. I'm ordering some just to find out.
11 Gauge Fiber Wads. They fit tight in my hulls.
10 Gauge Over Shot Cards.
I use a variety of Black Powder, Goex FFg, Old Eynsford 1-1/2 or FFg, mostly whatever I have on hand. Sometimes I go cheap and use Graf & Sons brand. I also use the "Holy Black" in BPCR so my inventory varies.
Your favorite method to seal the Overshot Cards.
Make sure the primer pockets are prepped. When the Primer is properly inserted they must be flush with the case head. If they stick up you would stress the shotgun & worse when closing the action or fireing, not good. The vintage original brass have only needed cleaning in my experience. The Magtech are hit and miss. Their 12"s didn't require much preparation. The 16's: Needed to uniform the flash holes, they were too small to be able to remove the primer after fireing. They also weren't deep enough or big enough around. With proper tools all of those defects can be overcome.
Others will give you additional help, I'm sure.

Bruce, who made or makes the sizing cylinders?

Those are vintage Ideal/Lyman sizing dies, Purchased them on eBay with an assortment of loading supplies, procured by the seller from an estate sale.

my 8 ga resizer looks like these tools.....nice find....charlie

Are they designed to be used with a mallet, driven on and driven out? I’ll keep an eye out for them in any case.

I lube clean hulls and tap them into the die flush with the base using a rawhide mallet and tap them out with a wood dowel that is a good fit inside the hull. I have not annealed the hulls as I do not use any crimp just secure the overshot card with Duco cement. (clean the interior with a copper fitting cleaning brush to remove any left over glue residue). After many uses I have had a few show a small split at the mouth and even fewer with a split down the hull. There have been very few failures and they will last for many reloads. I use these some in 3 hammer guns so the size die is necessary for me. Look for them as they will show up now and then. Great fun using them with black powder!

https://www.ebay.com/itm/32457571772...kAAOSwv45geftj

Regarding sizing dies does anyone have an idea if these are actually sizing dies and what brand these might be?

I used one or another Mec presses to reload brass shells, and for that reason I used 10ga OP and OS cards. Used the 11ga cushion wads. From shooting muzzle loaders for over 50 years a tight fit was usually used. To get a tight fit with Magtecks a 11ga wad, OP and OS, weren't getting the job done. There's a mechanical advantage when using the Mec that allowed using two sizes bigger wads. Just my experience.