Answer:


  1. On the vertical axis we find the percentage identity between the model and template sequences. The horizontal axis indicates how long the bits are in those two sequences that actually could get aligned. Above the curve, you find alignments that are good enough to allow for homology modelling. Below the curve we just don't know.
  2. False. Below the curve we don't know. We don't have good tools to tell us if the sequences are homologous or that they accidentally look a bit like each other. But if you have other knowledge that tells you that modelling should be allowed, then go ahead, build your model. But be careful not to trust the model too much...
  3. It isn't in the plot, but at 52% height far to the right of the plotted part of the curve.