Flashing occurs when the patched area has a different texture or absorption rate than the surrounding wall. Always use a high-quality primer over patched mud before applying your top coat. If texture is the issue, you may need a light skim coat to blend.
First, try placing a wide rubber band flat over the screw head and pressing hard with your bit. If that fails, invest in a screw extractor kit, or use a Dremel tool to cut a new flathead slot into the top of the stripped screw.
It depends. You can often float laminate or vinyl plank over existing hard surfaces (like old vinyl or tile) if they are completely flat and structurally sound. Never lay new flooring over carpet, and be wary of trapping moisture over existing wood floors.
Usually, this indicates a dull blade, pushing the material too slowly, or an improperly aligned fence (causing the wood to pinch against the back of the blade). Clean your blade of pitch buildup and check alignment immediately for safety.
Look for clues: electrical outlets are almost always nailed to one side of a stud. From there, measure in 16-inch increments. You can also use a strong rare-earth magnet to locate the drywall screws driven into the studs.