I'm afraid your post should have a trigger warning for some folk.
I didn't recall a preamp in those guitars but searched "Cort Flying V" and first thing that came up was a nice blue one on Reverb with a fair amount of info showing the switches and what they do including turning on the preamp...
Been a while since I watched that but I recall it as a sort of off the cuff performance.
For what seems on the surface a rather simple Chuck Berryish tune the changes are a little tricky. Likewise the lyrics.
I have purchased an MIK Squier just for the neck but NOT sans frets! Having to fret the neck seems like way more trouble than needed. I gather the OP is not in the USA but even in the current pandemic here there is no shortage of used Squier instruments that come with necks with frets.
If the pickups are both the same model P90, the bridge will normally have less output due to the strings having less arc of motion near the bridge. You can possibly help some raising the pu or polepieces. Or put in a different pu.
Generally, the way estate sales work is that there is a line or sign up list for people to get first crack when the sale begins. Lots of people waiting means limited numbers in at a time til the crowd thins. The pro pickers check the ads or get notified by the estate sale folks email and are...
Gets too blurry when I enlarge the photo. Looks like a Mosrite which fits with the Buck Owens/Bakersfield origins. Not a Ventures model and one of the other brands related to Mosrite and that area of CA could be candidates. Hall etc.
I wouldn't call that a hoarder situation. If you want to see a real hoarder house, check out the "Potter's House" series that the Curiosity Inc. guy has on his YouTube channel. I'd include a link but am too much of a Luddite.
If I lived near the sale in the above clip, the mention of radio...
I think the reason MIJ has become a feature is that the main source of made in Asia instruments currently is mainland China and after Cort left Korea, Indonesia. MIJ production became competetive qualitywise with USA circa the late 70s.
Back in the day a reasonable setup came with purchase. From your description you may have enough of a valley in the neck that you have a buzz. Tighten the rod a tad or ask the store to evaluate your neck relief.