I cannot answer all your questions, but I hope to help with one.
I completed an award booking earlier this year (UA miles, booked by UA 1k desk) for Eastern US -> TATL -> BKK in F and the "cost" was 140,000 miles. This was a star alliance award (UA,LH,TG as carriers).
I am not sure where you found the 170,000 mile cost.
I am just getting up to speed on all the CO details, so if you can reduce or eliminate fees by booking with CO, I do not see a downside. Miles transfer easily between UA and CO accounts.
I will defer to others regarding the MPM and routing details. I am still a novice with those, but I am trying to learn fast.
Good luck.