Buildings *shouldn't* really have walk animations. Save for ancients (night elven buildings, like Tree of Life), but I doubt people make them, so that could be one criteria. Another one could be the presence of the Stand Work animation, which is played during upgrades and unit production, so a double check for a lack of walking animation and presence of working animation could separate buildings from other models.
Dissipate is the animation when a Hero dies and gets lifted up in the air, while regular units have Decay animations. Some people like to add to their models both a decay and a dissipate animation so the model can be used both as a unit and a Hero.
As for team coloring, units and buildings in general possess some form of team color, but there are certain unit/building models which for obvious reasons (one unit per map, key characters, etc.) don't have team color.
If it's possible, you can go through a number of beta stages for sorting during development. The whole system would require a rather complicated algorithm as far as I can predict. You can go for automatic sorting if conditions x, y and z are met, but, for instance, if conditions x and z are met, but not y, then a moderator should confirm sorting. That could be one way of doing it, but I'm no programmer. I'm sure you can think of something better if possible.