Simple questions first.
Don't need to change the plugs unless your old ones need replacing, don't need to get the car set up after.
It's not just plug and play, it requires removing the coil loom (6 coil pack plugs and 2 other plugs) from the car and stripping the insulation off, then following the wiring instructions. If you follow the instructions exactly as they're written then you won't have any problems at all, it's really simple and requires rewiring 7 wires. The 12v power feed for the coils, and 6 trigger wires for the coils.
We've not got any engine dampers I'm afraid. Sorry!