ST1000 Tillerpilot and ST60+ Compass

[DeltaBravo60604]

I have yet to install my Tillerpilot. I had some mechanical issues with mounting the bracket. However, I also have a logic/data question.
If I have a ST60+ Compass with heading data and also a ST1000 Tillerpilot with heading data, if they are both connected via Seatalk, how will a conflict be avoided?
A related question is that the ST60+ is finicky. Sometimes it locks up, sometimes its blank and sometimes it works. It is the last of four Seatalk instruments in the string. I was guessing maybe it was power, but at least the spade connectors appeared in good order. So the second question is where do I look to diagnose an intermittent ST60+ Compass?
So to tie the two questions together, whatever is wrong with the ST60+, if that quits, how will that affect or be affected by the ST1000?