I can attest to #1. If partner airlines have seats, I'd rather

use partners, especially with the lousy services or no services you get with US airlines.

You can also combine partner airlines if you make the call.

Last year I used NW mileage on Air France. This year, I used UA mileage partly on ANA. Both Air France and ANA provide much better services/food/wine and much better looking and friendlier flight crew than their US counterparts. The $15 service charge is worth every penny. Take your pick, would you rather be serviced by grandmas/grandpas with pot bellies than by handsome young shuai ge/MM? :-)))