b ) The Andrastians religion is forced on a lot of people by Orlais and the chantry. Most of the people in Thedas would give a flying f... if the chantry would be destroyed, because in their eyes a powerful instrument of orlaisian oppression would have been destroyed, and in no way their connection to the maker. If they even believe in the maker. Don´t forget Kolgrim considers himself to be Andrastian as well, but in his case she is a dragon.
Actually, most people seem to believe strongly in the Chantry as devout Andrastians. I'm sure most people aren't aware of the politicking that happened between Justinia and Lambert, only that the seekers and the templars have gone rogue.
I'm sure most people wouldn't have cared at the time it was being forced upon them, but most people have been living with family members as believers for generations. The Avaars, Chasind, Dalish and the Qunari are the only groups that don't outright follow the Chant of Light. The Rivaini seemed to follow it as well as their own traditions before they were annulled, and the common man didn't resist the Chantry so much as they resisted the Chantry trying to force their views on how mages should be treated on a country where mages have an honored place in society. Most Rivaini's probably wouldn't care if the Chantry kicked the bucket after the annulment however (and that is just speculation based on the lore we already have and how much they revere their seers.)
I'm actually kind of interested in what role the Chantry will play in Inquisition. They have no Circles under their control, the templars and seekers for the most part have gone rogue, and the Chantry seems to be going through a great deal of infighting since we know that many Grand Clerics don't like Justinia V, and I'm probably remembering this wrong from Asunder since it's been awhile since I read it, but didn't Lambert want to have her assassinated and replaced with a Divine more malleable to his way of thinking?
I'm pretty sure I remember someone, somewhere in the book said something like that. If I'm wrong, then I'll just have to say "woops" but the Chantry no longer has the political clout or the military arm to enforce anything. At this point, the threat of an Exalted March is almost laughable with how little power the Chantry now has.
It'll be interesting to see how the Chantry develops when all they have are likely to be a handful of templars and seekers, maybe a few loyalists, and their sugar daddy country Orlais too busy fighting itself to help them out.