Replace C70 with eS78

[TexasPilot71]

I have a C70 MFD, through hull traqnsducer, and radar on our boat (a 27' single I/O powered cruiser), but no autopilot. I would like to replace this system with the eS78/Quantum radar bundle. This seems like a rater simple replacement, but I have some questions:

1) With the C70 (and latest firmware) you must have a separate electronic compass in order to display radar returns over the chart. Does the eS78 have the same limitation? How does it get heading information when sitting still? Can it? Is there perhaps an "internal compass" in the unit itself?

2) What components would I need in order to have a functioning autopilot and would all autopilot controls be driven via the eS78 or would I need an additional autopilot control module?

3) I saw a Raymarine video on the Quantum radar. In this video it showed two cables while the narrator talked about the fact that you only need a single cable for power. Questions: Can I utilize existing power cables (from my C70 system), and can I use existing data cables and forego the wireless radar? If I forego the wireless radar, will I still be able to "stream" radar data to an iPad?

4) Lastly, I'm not sure what transducer I currently have on my C70, but it's through hull. Would this transducer likely work if I went with the eS77 unit understanding I won't have "Downvision" capabilities, but would prevent me from having to drill another [censored] in the boat?

Thank you for your help. I plan to purchase in the next few days.