Not sure what you mean, but classic rewards are usually booked under the operators code, regardless of codeshare arrangements (exceptions may apply, your mileage may vary, etc etc)
No real change in the level of spam I get. Stacks of it.
It does go through waves of different things. Lots of online casino bonus stuff last couple ofdays
If you don't stay at ICs there's probably no benefit in it. I find the once a year weekend night certificate works for me, and the other bits and bobs help.
Only worth buying of you can use the benefits
Some background here, and also a suggestion Marriott is on the shortlist.
https://www.businesstimes.com.sg/property/intercontinental-singapore-bugis-close-frasers-owned-property-be-rebranded
I can't say I've ever had too many problems - even Turkmenistan was just a paperwork exercise.
Most complicated have been the ones where you have to turn up in person for an interview or something, but they are few and far between.
One problem with the current debate is that people are conflating "surcharging" and "interchange fees". While they are two different issues, the media seem to be mixing them all up into one pot.