My wife and I use soya milk instead of cow's milk. It is fine when added to tea, but when added to coffee it curdles horribly. Why?

I order a coffee in Planetbucks. It comes as a cup of black coffee and a little jug of cold milk. I decide to postpone drinking it for 5 minutes. Should I put the milk in immediately or just before I drink it in order to have it as hot as possible?

On the vaporous surface of freshly brewed tea grows often a thin layer of scum. You will observe on the attached video that not only this layer appears to be crazed, but also that the mosaic formed by these cracks regenerates around every second in a new different mosaic, like a mosaic slideshow. This phenomenon may also be observed on very hot coffee. It looks like a chaotic phenomenon. The attached experience was made in a bowl with very hot plain water and green tea. The cracks suddenly propagate across the scum layer and produce a new mosaic. How to explain such a difference between the patterns ? What make the crack propagate ?

I understand  that a cholesterol-raising chemical called cafestol is present in present in greater amounts in filter coffee than coffee made from a French press (also called Cafetiere), but I'm not sure how much Cafestol an espresso contains.

Larger grains seem to be repelling smaller ones, but the smallest ones don't repel each other. What's going on?

Hugh Young, Pukerua Bay, New Zealand

I often fill the kettle from the hot water tap in the hope that perhaps this will save some energy; however, if any of my friends are around whilst I am filling the kettle in this way, I am promptly told that the water from the hot tap is dirty and they certainly do not want tea made with this water. I then argue that the water will be boiled in the kettle, and that the spout of the kettle has a filter, so any nasty things will be killed or filtered out. My friends argue against this. Could I be wrong?