Wonderful - Thanks for not forgetting about working on the 3-D Globe!!! It really makes more sense to see our world that way... especially if you want to see how the weather systems form and move around.
Here I have searched for Dublin and by default it shows the forecast box at the bottom of the screen, which is fine. However once you click the X to close the forecast box you also lose the location dot and therefore making it hard to tap on the location searched for, in this case Dublin, to view the data for selected layer (Wind, Humidity, Clouds etc....)
It is "above the level of the model orography". So principially it is AGL, but be aware of ECMWF model resolution which is 9km, i.e. terrain is sampled with 9km step. So if you are in mountainous terrain, you can not rely on it, do not use it for planning in such cases.
More about Cloud bases: Can you tell us what do you use it for? Are you a pilot? We are thinking of adding new ECMWF parameter called Ceiling, which is similar to present Cloud base parameter. It may be interesting for you. If you want to know more, you can read this short description: https://software.ecmwf.int/wiki/display/FCST/43r1+new+parameters%3A+Ceiling
What do you think about this parameter? Would it be more useful for you than Cloud base?
"Surface temperature" is at 2m above ground. Respectivelly 2m above model terrain.
Higher temperature levels are placed in certain "isobaric levels". If you want to recalculate the isobaric level to altitude, you can switch to "Geopotential height" overlay which shows you the altitude (AMSL) of the specified isobaric surface.
If you are asking for the altitude of zero-degree isotherm, you are lucky man/woman, because we are planning to add it as a new overlay soon - maybe next week.