Just some additional comments:
"2. I have noticed the default choice of first worker seems to be more production based so early manual intervention is often required."
Now I have no own experience with c6, just watching people play. As I remember, they used food+production priority or no priority at all. Would be interested to know, whether it works without intervention, if ONLY food becomes prioritized (in the beginning).
"3. Power tiles (anything 4+ of food or prod, or 5+ combo of the two) are of limited use for a first city in ring 3 and are a necessity to have 1-2 in ring 1,2 for a strong start."
IIRC, the city governor buys usually first the best tiles from ring2, so one can expect to get them quite soon. But then all the rest from ring2; i.e. special tiles from ring3 will take too long, those must (and should) be bought ASAN (possibly with a ring2 tile in between).
"5. A defensible position has some value on immortal/deity initially but should not be a major contributer to a decision."
After a STRONG START the defense value shouldn't be too important.
@
DanaLea: for a start you can just move onto a adjacent flatland and settle still in the first turn ...