... this is especially interesting, when you make use of the to be replaced item in other layers as well and don't want to replace the item for those other layers all together
I'm sorry but I don't understand your question at all. When you replace footage in a timeline all of the animation and effects remain unless the footage layer is a Shape Layer because Shape Layers don't have a source. They are mathematically generated entirely in the timeline. Everything else should replace an new layer and retain all animation and effects.
If you have animation in Layer 1 and you select Layer 1 in the timeline and you use Alt/Option + Drag to move footage from the Project pannel to the Timeline the footage in Layer 1 will change but the animation and all the effects will remain.
If you want to keep the Layer 1 and add another footage item but you want to add another footage item from the Project Panel but use the animation applied to Layer 1, then duplicate Layer 1 by pressing Ctrl/Cmnd + D, then select the copy, then use Alt/Option + Drag go bring in the new footage element to replace the duplicated Layer 1 (layer 1 copy) and retain all of the animation.
Thank you. "Alt+Drag" it is. I was looking up exchange item, replace footage etc. in google, youtube and user manual, but didn't come accross Alt+drag other irem on layer.