Why you are able to sip hot tea faster from a saucer rather than from a cup?
The (rather disgusting, uncouth and common) idea of transferring tea to a saucer before drinking it (noisily), is to cool it down faster, because of the larger surface area provided. The relatively thin layer of tea, also aids conduction through the saucer, cooling it even faster. It's a matter of temperature, more than viscosity or speed.
You can drink hot tea (or any hot beverage) faster from a saucer than from a cup because tea has a larger surface area exposed to the air when it is in a saucer. Because the saucer is wider and shallower than a cup, more of the tea is in contact with the air, so the heat in the liquid is able to dissipate into the atmosphere more quickly.
Why might sugar dissolve faster or slower in tap water than water with sugar already dissolved in it?
There is a point where the water/sugar solution will become saturated and no more sugar will be able to dissolve into it. It would dissolve faster in heat and also where there is a higher water:sugar ratio. When there is a lot more water particles than sugar particles, the sugar is broken down faster. Is there is sugar already in it then the the solution will have both sugar and water particles rather than all…
With current empirical science nothing is known to be able to travel faster than light. However theoretical science is able to consider faster than light speeds. ____ Imaginable, sure. :) Lots of Science Fiction writers and scientific theorists have talked about FTL (faster-than-light) travel. We have a ways to go before we find out if those things are actually workable in the real world, but they are definitely imaginable. :)