Yeah, that frame is too big for you. You could drop down to a 70mm stem but that would noticeably change the way it handles.
A steel frame with a carbon fork will put you in a bike you had before. It's almost exclusive to racing bikes for people who want to ride steel but also want to still be a weight weenie. It sounds like you value comfort so I would recommend an all steel frame unless you were going to lift it a lot.
A lot of the things you're looking for are reasonable and practical which, since this is the bicycle industry, means you don't have a lot of off the shelf options. How luxurious can you get? I think something
like this from a company that only sells frames would be what you're looking for. (Reading your post I actually kept thinking, "This has got to be a Velo Orange commercial, right?" They have a lot of the accessories you're looking for too.)
If you can't get that expensive I would suggest looking at vintage frames. Cyclo-touring used to be popular and there are tons of "comfortable, but quick" frames that were built for that purpose. Since you want to convert to single speed a 5 speed frame is the easiest type to work with because modern day track wheel hubs use the same frame spacing at the rear (120mm). There are lots of good frames from the late 70s, early to mid 80s that shouldn't be discounted though.
If you go vintage I would advise against anything French. I own a vintage French bike and I love it but all of the parts are standards that were specific to France so owning one is more of a hobby with a benefit than a mode of transportation.
Whichever option you elect I think you should prioritize a bike with a threaded fork. Threaded stems let you adjust the height of the handlebars and the distance away from you. It's not a common design anymore because it costs more to produce but they still exist and all bikes before 199X had threaded forks on the road.
There's nothing wrong with rim brakes. They're just fine. Unfortunately pushing disc brakes has been an easy way for the bigger companies to turn sales so disc only frames are not uncommon now. Tektro makes a cable pull disc brake (the Spyre) that preserves simplicity while being a disc brake.
I think you might find
this podcast informative RE: tire size and pressure.