Point further down the fall line. There is no boost button and no accelerator - gravity is your engine, and how much of it reaches you depends on the angle between your board and the slope. Riding straight down is the fastest and least controllable line on the mountain; cutting across is the slowest and safest. Tucking (Space) sheds a little friction and takes away some of your edge, which is the same trade in miniature.

Those are ice. Your board still turns on ice - the input is not being ignored - but there is almost no edge grip, so your velocity keeps going the way it was already going while the board points somewhere else. You slide. That is what ice does in real life and it is why the fast line and the safe line are rarely the same line here.

A storm front coming down the mountain at a fixed speed. It does not speed up or slow down, so it is not a rubber-band difficulty system - it is a clock. You do not have to outrun it in any given moment, you have to average faster than it over the whole descent, which means a crash costs you far more than the speed you lost in it.

Hit a ramp and steer in the air to spin. The spin itself is free; the landing is not. When you touch down, the game compares where your board is pointing against the direction you are actually moving, and if the gap is too wide the edge cannot catch and you wash out. So a big spin is a bet that you can square up before the snow arrives.

Points, and a reason to leave the fastest line. Passing between the poles is worth a bonus, but the gates are not placed on the racing line - going for all of them will cost you speed and put you somewhere on the slope you would not otherwise have chosen. They are optional on purpose.