Passive tube means you'll need to provide your own amplifier to push it. Amplified means the amplifier is built into the tube. No, you cannot push a passive tube with the tiny amp built into your source unit.
Speaker inputs (often called High-level inputs) mean regular speaker wire inputs. Tie them to the speaker wire from an existing speaker in the car. Pre-amp inputs (often called low-level inputs) are RCA connections. You'll have to run RCA cables from your source unit (deck, head unit, radio, CD player, whatever you want to call it). Either of these style inputs just provide signal to the built-in amplifier.
And yes, you can install the marine equipment in your automobile.