Old building (1938) Insulation and renovation

Hello dear forum members,

First of all, I hope that I am posting in the right forum, as this is about insulation, but I also wanted to address other things and did not want to create multiple threads.

Preface to the project:

I recently acquired a house very cheaply (basement, ground floor, upper floor, and attic) with an area of 64m² per level and am currently renovating it with my rather limited means (as much as possible by myself). The house is/was in rather poor condition but was occupied until recently. All installations (electricity, water, house connections) are being renewed. The masonry has a wall thickness of 36 cm and a cavity in the middle, which was apparently common at that time.
The roof was the first thing to be addressed; some tiles were already broken and the wood also had to be replaced. A roofing company and a carpenter from the family helped me here. So the entire roof (except the beams) was renewed, including 120mm insulation with foil and everything that belongs. For cost reasons, I could not use thicker insulation, as this would have required a recess etc.
The facade was insulated by the previous owner about 5 years ago with about 4cm thin polystyrene boards and plastered (specialist company). The facade still looks good and hopefully can stay that way for the next few years.
Currently, I am working on drying out the basement. For this, the entire basement was dug out down to the floor slab, swept and edged. It should air dry for a few weeks before the 2-component thick coating (6mm according to the manufacturer) is applied. Then 40mm Styrodur boards will be installed, and it will be refilled with the excavated soil (mostly gravel) (not every work step has been listed). The basement is 1.30m deep in the ground (where the floor slab will go) and protrudes about 80cm above ground. Here comes my first question: how high should the insulation and the thick coating be applied?

The facade insulation starts only above the 80cm from the basement, basically from the basement ceiling upwards. This upper part of the basement looks very well preserved (red clinker bricks).
Inside the house, I have removed all plaster down to the base walls and the floor (old wooden floorboards including slag) has been taken out; the floor is a masonry concrete slab. The next steps are to lay the electrical, water and wastewater pipes as well as install underfloor heating on the ground floor and normal radiators on the upper floor (here the floorboards remain due to the wooden beam ceiling). As a heating system, the company Viessmann was recommended to me, and I decided on a liquid gas heating system including tank (which I have already buried). I also bought new windows because I am not a fan of box windows (optically speaking). These are windows from Praktiker, double glazed. The front door was also renewed; currently there is a rather dilapidated wooden door, now a plastic door is waiting to be installed.

I am wondering whether the things I listed are good or if I should/must consider something else. There is no historic preservation and regarding energy regulations I do not have to comply further as it is apparently declared as repair/renovation or something similar (statement from the roofer).

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Hello,

I have edited your post for readability.

Best regards from the Rhineland
Building expert

Thank you @Bauexperte, something seems to be wrong with my PC, it removes all line breaks...

Hello,

....I recently very cheaply purchased a house (basement, ground floor, upper floor, and attic) with an area of 64m² per level and am currently in the process of renovating it with my rather limited resources (as much as possible by myself).

Purchase based on gut feeling or with the support of a professional? Initially very cheap can very quickly turn into a bottomless pit for laypeople!

Best regards

.. you mean so-called "bargain houses" ...