What do I need regarding preamp/cartridge matching?

Cartridges require no special pre-amp. If your amp has one built in the sound from the deck will come out at the same level as other functions. If the amp has no inbuilt pre-amp you will still hear sound (if the cartridge is working) only the volume will be too low to listen to. All you need do is connect the record player to the amp and see if you can hear the sound. If you can't then you need a magnetic cartridge pre-amp. By the way if you need a new cartridge you don't have to stick with a Gemini make. You can use any one you want as long as it will fit into the headshell. There some better makes of cartridge out there, that will give better sound quality. It all depends on what you want to spend on a cartridge!