The bolts are shouldered, meaning they hit solid at the last. If it leaks then you get to do it all over, you absolutely cannot over tighten bolt to stop leak since the gasket can get no tighter once you have bottomed the bolt. The bolts are not really hardened, you will break them like so many others here do then fun city. Simple job turns into nightmare...........
Clean and dry and it'll work flawlessly, get sloppy and leave some crap in cover groove and you probably get to do it over. No need for any sealant except maybe a small dab right in the corners of cam caps. Tighten all bolts evenly, the gasket is thick and can roll the sealing edge over to not seal if you tighten a whole bunch in one spot without rest of the cover coming down with that spot evenly. Look at gasket close too, I've seen pieces of mold flashing that could interfere with sealing. I peel them off.