What, precisely, is it that you wish to discuss?
Brains don’t work the way you suggest, i.e. being able to download memories. They don’t contain literal bits that give flipped from 0 to 1 to store data. Memories and psychomotor responses are stored in the structure of the brain itself, forming new connections between neurons. To reproduce the brain you would essentially have to dissect it at a cellular level, and even then, you probably could not reproduce memories per se; just a similar set of neural patterns which may or may not come together in anything like an actual memory.
Even the simplest living organisms are incredibly complex, many orders of magnitude more complicated and reliable than our most sophisticated machines or computers. A protozoa is a highly complex organism with self-repair and motile capability, and yet is basically the most simple phylum that could be considered animal-like. Spiders are masters of mechanical complexity and efficiency, and by the time you get to something like an octopus or primate, the degree of sophistication is something no human designer could even contemplate.
Swapping out parts in the manner suggested in the o.p. is purely science fantasy. We’ve just recently achieved the level of understanding of molecular physiology and neurology to be able to influence basic things like growth factors and replication in a controlled fashion. Sequencing the human genome was done only within the last year, and growing or manufacturing new body parts capable of being seamlessly grafted onto the body is far, far more difficult than just replicating a few strands of DNA.
It will be a long time before we have anything like the technology suggested by the o.p., and even then it will be nothing like swapping out components in a PC tower. It will be more like building rehabilitation and restoration writ large, with the additional challenge that if you place a single bolt or tile out of place the entire building starts to tear itself apart.