The orange device is probably a diode, used as a temperature sensor - reuse the existing one (just leave it connected to the white wires as it is) as you've no idea what type of diode it is (and no way to find out). There's also a fuse connected between two of the batteries, you can either carefully remove it and reuse it, or you can buy replacements from RS, Digikey etc.
We make up LOT'S of battery packs at work, so have a spot welder to assemble them, we also keep various values of fuses in stock to avoid using the old ones. We also keep various temperature sensors and connectors (so we can make certain new packs from scratch), but it relies on been able to identify exactly what the temperature sensor actually is.
We also keep multiple sizes of heatshrink, to professionally finish the pack - you can buy pretty well everything from Cellpack Solutions - worth a google.