First 3 pics are new, the 3 are the day I got them at Walmart. I’m a greenhorn, experts is this a TBMc as many people suggested back in March? Sorry that the camera angles don’t match. Ty in advance!

Just found a cacti in my greenhouse that has some mealy bugs! Whats your go to treatment process. Its starting to get colder here and I would love to stop these guys before they spread to the rest of my plants in there. It only appears to be this one plant. Should I remove its direct neighbors as a precaution?

Google said it looks like a trichocereus grandiflora hybrid any advice helps :)