What’s…?

I hope you’re not angry with me but I have no idea of Car-hifi !!! I was advised to use the search function but it doesn’t really make me smarter and lasts a long time, so I have the following questions: 1. What does 2-way, 3way, etc. speakers mean? 2. What does 2-channel, 3-channel,… etc. amplifier mean? 3. Does power amplifier mean = amplifier and if not what then? 4. for what is amp the shortening or what does it mean? 5. What is the difference between bass box? and roll and why is the role supposedly better? and 6. what would you recommend for an equipment for an Opel Astra 1.6 4-door 99er Bj? (still all original)