ᐅ Old Wooden House: Questions About Insulation

Hello
I have received good advice here before. Furthermore, I had my renovation planned by an insulation professional, but I want to carry out the work myself. Therefore, before starting, I would like to ask a few detailed questions:

• The rafters under the wooden roof will first be insulated with 10cm (5 inches) of Homatherm. Next, an additional 10cm (5 inches) layer will be added horizontally and insulated the same way. Then a vapor retarder will be installed, followed by a 40mm (1.6 inches) layer of Homatherm ID-Q11 (see diagram below). However, the rafters vary in height between 10 and 15cm (4 to 6 inches) (layer 4). This means that at the higher rafters, there would be an air gap up to layer 5. Or do I simply need to buy Homatherm in different thicknesses and fill everything up accordingly?

• The exterior walls will also be insulated from the inside. First, insulation will be installed between the studs (10cm / 5 inches), then an additional 60mm (2.4 inches) layer on top. This will be followed again by a vapor retarder and then wood paneling or drywall. However, in some areas, the horizontal wooden boards of the walls have small gaps between them, with openings up to 3mm (0.1 inches) high. Do I need to pay special attention to these gaps, or can I simply press Homatherm Holzflex insulation between the studs?
• Should Homatherm be installed directly onto the wood, or is it recommended to secure it additionally with adhesive?
• The detail in the two side attic rooms is also quite complicated. The build-up throughout is planned according to the diagram above. However, at the level of the sill plate (see photo), there is a cavity extending to the eaves. Can this cavity be left open, or do I need to consider something specific here?

• In the upper image, top right, is the transition to the roof (see bottom image). Here, as the bottom photo shows, boards have simply been nailed into the gap. Installing a vapor retarder here (the gap is only about 5 to 10cm (2 to 4 inches) wide) is impossible if I want to follow the roof build-up shown in the top picture. Can I connect the vapor retarder simply at the top and bottom to the wooden boards (using sealing tape and then stapling it firmly), even if the transition isn’t 100% airtight? Here is a sketch:

• At the top inside the attic itself (see photo below), I have the same problem from the other side.

• Additionally, the question arises as to how I should proceed around the chimney. In 2009, a new oil heating system with plastic flue pipes was installed inside the chimney, so it no longer becomes very hot. I am planning to insulate up to the mortar surrounding the chimney. Can I tape the vapor retarder there, or will that not work? Or should I continue the Homatherm insulation right up to the chimney?

Thank you very much in advance,

Nick