The exact guitar that you described does exist!
Squier Classic Vibe '50s Stratocaster Electric Guitar in White Blonde https://reverb.com/item/29650330-squier-classic-vibe-50s-stratocaster-electric-guitar-in-white-blonde
Yes it is true. A boost into the front of your amp acts similar to overdrive. It makes your tone thicker and more compressed, but not louder in volume. A boost in the effects loop will make your volume louder.
As a buyer you don't need to be concerned about lowball price. Let the seller deal with that. What's the worst case that can happen? He refuses or totally ignores your offer, and you buy it at his listed price. Or, he could counter-offer you with a price in the middle. Also don't forget to...