All generally true, though weight loss goals are special.
The road width will adjust to accommodate 90% of your daily variation. I also have days where I’m more than a kilogram above or below the previous day’s weigh-in. Eyeballing my withings graph, it looks like each lane of my road is 0.9 kg wide
Also, there’s a guarantee in place for daily-weighers that if you’re in the blue lane or better, tomorrow’s fluctuation won’t derail you. It’s imperfect, but can be useful on occasion.
There’s a moving average plotted on the weight graph, so you can tell whether you’re on a downward trend. If most of your dots are below the average, your mass is decreasing. But there are loads of reasons not to beemind the moving average.
As always, make sure that you have goals that support weight loss.
PS: regarding #1, retro-ratchet can soak up any unwanted safety buffer, though it can be tricky to apply to weight loss goals.