Until some time ago, there were two major systems for labelling film speeds. One was ASA (American Standards Association), the other was DIN (Deutsches Institut f|r Normung). The ASA system had the advantage of being linear (doubling the number means that the speed is doubled), and the DIN system had the advantage of being logarithmic just like the film (an increase of three degrees DIN also means doubling the speed, or one f-stop more). It has been common for a while to print both scales on cameras, and the ISO (International Organisation for Standardization) drafted an International Standard. The labels 100 ASA and 21 DIN, which are equivalent, are now shown as ISO 100/21.(posted 8859 days ago)So there is indeed no temperature involved in this. The temperature shown beside the little thermometer pictogram is probably a warning not to expose the film to too high an ambient temperature for this might cause fogging.
As for the E.I.: There is also an ISO standard for measuring film speed from characteristic curves obtained with standard development. It involves evaluating the density caused by a minimal, just-above-the-threshold exposure and the local slope of the curve. We all know that changing the developer may change the film speed. So the term "standard development" implies that you may encounter deviations with your specific set-up. Many photographers therefore calibrate their films and meters for themselves to exclude this source of error. Such an actual film speed is strictly an E.I., or exposure index.
The second kind of E.I. is that for push, or pull development. Pushing and pulling change the gradient of the curve, the negative contrast. They do not really change the films ISO speed (they do, in fact, but mostly due to their influence on the gradient, and only marginally when compared to their effect on the E.I.). The "speeds" given for push development are then *apparent* speeds, as they are based on metering mid-gray.
So E.I. is actually a fuzzy term which is used for non-standard speed ratings.