Old building renovation, house built in 1916, multi-family house converted to single-family home, experiences

What does your experience say about to what extent it is sensibly possible to save by "waste separation," that is
1. what do the price levels of waste qualities mean for landfill disposal and
2. aren't they compensated by the need for multiple containers and
3. is this more of a theoretical idea from a work-economics standpoint?

I didn't separate anything. Only hazardous waste, of course.
By the way, neither the equipment nor the disposal nor anything else is particularly expensive. My experience with 2 renovations shows that you can indeed save very sensibly here. Container costs are just two phone calls away. And I also found companies more easily. Both plumbing and electrical were glad not to have to handle it.
Inform neighbors and go full throttle.

Well, that doesn't match our experiences at all. We invested hundreds of euros in tools, sometimes just borrowed them because purchasing would have been too expensive, or we borrowed them from family. Containers are at least quite expensive for us too. Mixed waste is almost unaffordable, so you separate it, but then you need several containers – you have to have the space for that. And annoying the neighbors with demolition work on Sundays for weeks, you can do that, but maybe you don't have to^^. In the end, we drove a lot ourselves to the landfill with the trailer and actually saved money overall, namely the container, and could dispose of everything separately. But it all takes so incredibly much time... we lived only 3 km from the construction site and could work during the week too. No idea, maybe it depends on the circumstances, but I can't say I would recommend it in this setup, so if you don't live on site.

The project start is expected to be mid-2022. I had planned to carry out the interior dismantling within 14 days. Tools are available and living nearby during that time is also not a problem. Would you first conduct an on-site inspection with the respective craftsmen for the various trades and then proceed with the dismantling, or show the craftsmen the shell construction? And does an architect also act as the on-site contact person or is another party needed?

14 days is, in my experience (now three such renovations), too short for a dismantling of 170 sqm. Unless you are 5-6 people. Is there [Denkmalschutz]? Has that already been checked?

There is (fortunately) no monument protection.

Do you have vacation and enough people? Otherwise, 14 days are hardly feasible.

Unfortunately, I have no idea about architects.

But I would look for craftsmen as soon as possible. They are sometimes booked up to a year in advance. Especially the really important ones like roofers, plumbers, and electricians I would start looking for soon. However, you first need to know what is supposed to be done. And for that, you need the architect. You should think about a sensible order for this.