There's only one kind of P pickups we make, so a photo for ID won't be necessary, but folks around here are addicted to pictures of basses, so I'm sure they would still be welcome.
The pickups are low impedance, and hence output and need a preamp to be heard at all. It should actually be so low as to be pretty much not usable without a preamp. The preamp we provide has an adjustable gain set with a trimpot on the inside of the instrument, so you can set it to match other basses you might swap between during a set.
If you like the bass acoustically, and it plays well, you might want to keep it. Adding an Alembic preamp (really all the electronics:output jack, volume and either a filter or a bass/treble module) will let you hear how the pickups were intended to work with the tone controls. If you have 2 split pickups, you'd also need a pan control.
Others will no doubt chime in their advice for selling - good luck!