Renovation of basement sealing and insulation / old plaster loose

Hello, We are currently renovating a 60-year-old house and have, among other things, exposed the basement. This is to be newly sealed, and the height of the external ground level will change. Previously, there was a step and a concrete platform in front of the front door. Both were removed, as the entrance is to be made flush with the ground. Now I have the following questions: - The old base coat plaster was/is loose in places, I have already removed most of the loose material. How should one deal with the damaged areas now? Simply apply bitumen coating over them, or must they be plastered beforehand? - Due to the higher ground level, the bitumen coating would actually need to be applied over the old topcoat plaster. Visually, it would not matter, since an ETICS will still be installed. Can this be done? - There are edges between the old basement and the basecoat plaster and between the basecoat plaster and the white topcoat plaster. How should one deal with these when the basement/base insulation comes over these edges? Many thanks for your tips

We looked at it closely again and decided to completely remove the old base plaster. Now, after patching, it has become a clean surface.