You can vape at the lower end (better for your coils if you hit it often), but too low and the juice isn't going to cook(vaporize) properly on the coil and it'll bubble/spit more. With the whole vapers tongue thing, keep your mouth clean (brush your teeth or your tongue at least) and use at least a couple of juices that have different flavour profiles, you can (for example) stick to fruits, but have a few different things to alternate between. Something with menthol will help, it doesn't have to be an all day vape, but it certainly works to cleanse the taste buds if you're wanna chug custards or whatever else. Sticking to one flavour will dull the tastebuds if you vape that and only that, have at least one thing you switch in and out.