Not a dumb question at all, in fact this may be the most important technical, or tactical, question in all of skiing!
There are two fundamental ways to slow down on skis, and you've described them both. One is using your skis as brakes--as in a braking wedge (not all wedges are this), a "hockey stop" (twist both skis quickly 90 degrees and dig in your edges), or an intentionally skidded turn, which is really any turn that begins by twisting your tails out away from the turn direction.
The other way is to go uphill, which will slow you down even if you do it as fast as you can.
Friction. Direction. Those are the two ways to slow down on skis, and good skiing requires mastery of both. But "direction" is the habit of all great skiers, who use "friction" only when needed. "Friction" (braking, although it also includes things like falling down) is, unfortunately, the habit of the overwhelming majority of skiers everywhere, from beginner to advanced.
The two methods are not compatible with each other, either. Controlling direction (line) means using your skis and their edges to grip and shape turns. Braking means using your skis and their edges to skid--to not grip--and scrub off speed.
So you have an understanding of both principles. Practice both, but seek to develop speed control from line (direction, finishing turns, going uphill to slow down) as your habit, gliding like experts do, keeping your skis moving the direction they're pointed as much as possible. Use braking moves whenever you need them, which will actually be quite often in many skiing situations (like the very narrow corridors, chutes, and couloirs that you mentioned). But if you can avoid riding the brakes, and thinking of turns primarily as a way to slow down, you will be far ahead of most skiers on the hill.
Think of turns as ways to control direction, and use direction to control speed. Think of turns as how you go where you want to go, not how you stop or avoid going where you don't want to go. Think of turns as offensive and braking as defensive. Great skiing is very much offensive!
Great skiers do not turn to control speed. Great skiers turn so they don't have to control speed!
Great skiers control speed with tactics (skiing "a slow line fast"). Most skiers control speed with technique (forcing the skis to skid and brake). Great ski technique is about controlling line, making precise, efficient--and fast--turns. When you can do that, and you use good tactics, you will need you brakes less and less.
It takes very good technique to make offensive, completed turns in a narrow corridor. Keep practicing short, round turns, trying to keep your feet moving the direction they're pointed. Make sure your turns begin by flattening your skis and releasing your edges--letting go of the mountain--and guiding your tips down the hill and into the turn, rather than setting your edges and pushing your tails uphill, or out into a skid (the bad habit of about 99% of skiers).
But remember--before this can happen, you must not want to slow down when you start your turn! When you make these good turning movements (release the edges and point your skis downhill), you will gain speed, of course, so the prerequisite is the desire to go faster when you start a turn--not slower. Not many skiers accomplish this, or even realize it. It's a big change!
Gotta go. Hope that gets you started!