I don't have a solid answer to your first question but I would imagine it is possible to wire the new style mirrors.
I am not sure how the rotary switch would look in the e34. I think it would look out of place but that's just me.
I know the connection from early to late production E34s are different, but is there a way to wire up a late model mirror to an early production E34?
Also, has anyone thought about or has done modding a rotary light switch (like an e38/9) instead of the sliding switch on an E34?
I don't have a solid answer to your first question but I would imagine it is possible to wire the new style mirrors.
I am not sure how the rotary switch would look in the e34. I think it would look out of place but that's just me.
no point, just a thought.
Just buy an E36 Krapwagen.