1. difficult to say exactly which font is this. Small sample, very low contrast and heavy jpg distortion. Can be one of several sans serifs.
2. Very legible sans serif fonts. Often specially designed to be very readable on a distance.
3. If you want to be absolutely sure that you are legally using fonts you can
a) buy a commercial font
b) ask the designer of a 'free' font for permission. Almost all 'free' fonts are free for personal/non-profit use. Most of the designers require permission asked for commercial use.
mumble on the side ... Weren't pictograms designed so that the message was clear without text? And if there is text why use a pictogram too?
Have fun and ... be nice to the cats
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Relax ... it is just a font