Please do a thread with pics when you attempt to change the batteries. It would be very valuable.
If you succeed and reuse the old sensors (keeping their original fr/rr orientation) then no computer is necessary. If you change them out entirely then no, it must be paired. All sensors use a discrete frequency or other geeky term to be unique, like bluetooth. Otherwise the bike couldnt tell the front from the back or from the beemer guy at the lights beside you.
Can't say about the epoxy other than to keep it light. The more weight at the sensor means more weight opposite on the rim to keep the balance.
Now with Double Triple Blacks.