Welcome!
The Cortex RAM card can almost certainly be fixed... (Zetr0
)
The battery in your A4000 is likely leaking and the acid is eating your motherboard - CHECK IT NOW and REMOVE IT.
The BPPC if not used by you will almost certainly get you £250 - £300 on Amibay, and the BVision should fetch £125.
http://amibay.com/
The magic64 key will need a little hunting... Did you try this version on aminet? I dont think it needs the keyfile.
http://aminet.net/package/misc/emu/MagiC64