Autopilot control head and course computer

I have a Luhrs Tournament 400 and the Cetrek autopilot needs replacing. All the other electronics are Raymarine, E90W, C70 and DS600x so I am going the used Raymarine route. Can anyone advise in simple terms the differences between 7001, 7002, 8001, 8002, st70 and p70 head units?

Do they all interface with older course computers?