re: finding studs. unless it's balloon framing, you'll hit the bottom plate in normal stick home construction (and if not, you probably should air seal that gap...). The most consistent and easiest way to find studs is hovering a neodymium magnet across the wall to find the drywall screws. I haven't used my stud finder in years b/c of how much more reliable this is. Plus, it works even if you've doubled up your drywall (e.g. 2x 5/8in w/ green glue for sound abatement, etc).