Just a short explanation of Ice Crystal Icing (ICI). Conventional icing (and most of the regulations related to icing) involves 'super cooled droplets' - i.e. droplets of liquid water that's at a temperature blow freezing. These droplets hit a cold surface (such as an aircraft) and immediately freeze. ICI is fundamentally different - it occurs when it's simply too cold for 'super cooled droplets' to exist, so the droplets freeze into crystals. ICI generally exists at higher altitudes (30k and up) and tend to form above convective weather systems (e.g. thunderstorms).
ICI is not a danger to cold surfaces - it simply bounces off. But, when ICI hits a warm surface (above freezing), it will melt. The danger is when there are high concentrations of ice crystals - the first crystals melt, but then additional crystals hit and cool the liquid water and it re-freezes - and large accumulations of ice are possible. This ice can often shed all at once, causing downstream damage to the compressor and quenching the combustor flame. We've seen ice form in compressors where the initial surface temperature was as high as 90F/32C.
Yep. GE came up with a rather clever FADEC algorithm that can detect ICI, and when ICI is detected the FADEC cycles the Variable Bleed Valves to dump ice out of the compressor before it accumulates enough to cause a problem. There was also an issue unique to the GEnx-2B engine on the 747-8 where the location of the fan support struts combines with the fan exit guide vanes to create an ice accumulation point, so there is a fix in the AD that re-clocks the exit guide vanes with respect to the struts to eliminate that ice accumulation point ( the -1B on the 787 didn't have that problem).