New Ikea phal bringing pests into my home

[thegirlwiththemouseyhair]

So, just when my original orchid, Oscar, has started recovering from many health issues, I decided to reward myself with a new orchid. I tried to find the perfect one on my last trip to Ikea and spent an absurdly long time inspecting all the plants. Unfortunately, about a week after bringing home a lovely phal, I noticed a few small, thin trails of white appearing on the undersides of the leaves. I did not think to take pictures, but it was not the gross webbing of spider mites - spider mites destroyed three potted plants of mine and traumatized me last fall, so I remember what that looks like. This white stuff was almost like a few tiny threads or dust on the underside of the leaves. I treated the plant with Safer's End All miticide and insecticide combo. (After those spider mites last fall, I just want to kill any pests with fire right away.) The first treatment was last Tuesday; I treated it again yesterday, after noticing maybe one or two tiny bugs, and a few more of the white thready things reappearing on the leaves. There were far fewer white thready things yesterday than a week ago, and it was a pretty small amount to begin with. I also killed one bug manually with alcohol on a Q-tip, and am obsessively inspecting the plant and cleaning any unusual dot (white or another colour) off with an alcohol-dipped Q-tip. I suspect aphids or maybe mealybugs, and I think the bug I killed manually looked more like an aphid, but am not 100% sure. My questions are these:

1) I have set up a bit of a quarantine with this new plant on one side of the living room, one orchid against the window, maybe 14 feet away from the new one, and another orchid against the opposite wall, maybe 8-10 feet away. Is this enough distance? I really don't want the problem spreading.

2) I think the first time I watered the new phal, before noticing anything suspicious, I had it on the counter beside one of my other orchids, and they touched a bit. Should I be worried? How obsessively should I be inspecting every white speck of dust (or is it a mite or an insect egg?) on my other orchids? I note that I treated the other two preventively yesterday, before reading that that's not something you can do regularly lest you help pesticide-resistant pests evolve - shudder! I could try to rearrange all my possessions to put the other orchids in the bedroom and maybe one in the bathroom, but that's not a permanent solution.

3) Should I jump the gun and repot the new phal, or keep treating it with Safer's End All for a few more weeks - or repeat treatment, then repot? Is there a schedule for these things?

Basically, I read through the threads here about pests and watched some YouTube videos, and I think this is a manageable problem, but really appreciate any tips tailored to my questions. Thanks in advance!