1 & 3. For now, go for it. HOWEVER, when Miranda echoes a Reyvateil body (which won't be for a long time) or mind structure (which would probably come first, in all likelihood) she also gets this thing called a Mind Guardian that will block attempts to do this. Technically the ability of a Mind Guardian to do something like that is headcanon, but a Mind Guardian's usual purpose is to facilitate Diving (in which someone else enters a Reyvateil*'s mind), thought-reading and imprinting would likely be considered some sort of unauthorized access and be blocked.

*Theoretically it is possible to Dive into a human if you have his or her specific mental map