Just to explain better what California is trying to say, 'tracking' is the spacing between the characters, where the same amount of space is added between all characters, including spaces. It's the '_' in this example:
T_h_i_s_ _is_ _t_r_a_c_k_i_n_g_.
Kerning is the space between pre-defined character pairs. It's meant to compensate the geometry of characters like 'A' and 'V' together. If you align them by their bounding box the space between their oblique shapes will be perceived as larger than strait characters like 'N' and 'H'. So in a font they specify that some pairs of characters overlap their bounding box by some pre-defined amount in order to compensate visually.
But I don't think that Kerning is absolutely necessary for this plugin, and probably would be extremely hard to implement. Having characters with variable width can be enough to avoid that 'l' have a bigger space around than an 'M' for instance.