htech says:
1. You can keep it as a Pride. You can also add "Shapeshifting" as one of your D10s, but that would be an extra dice, if both apply. Your call.
2. The difference starts with the roleplaying/reasoning behind it... Is it an specialization of a skill, something that could be learned by everyone that is good at it, or something extraordinary (ex: darkvision) that you're "born with" or so unique that doesn't fit a single skill and could be seen as a combination of multiple ones?
3. They do. They can break/fail or otherwise help you with the disguise even if your attribute+skill rolls lower. That's represented by the dice in it.
4a. Teleportation is not possible in this magic system, at least not that the PCs know of. Seeing/hearing other places is possible through the Perceptio school.
4b. Some of that is not possible in this magic system. You can enchance an already present capability to extraordinary levels, balance in a flimsy branch or transmute matter, but not to steal through solid glass or something like that
4c. Changing/influencing other people's dreams is covered by Dominatio. Seeing/hearing, even something in other people's dreams, is possible through the Perceptio school.
4d. Light manipulation is covered by Illusio. Pure shadows (ie. just make it dark) by Excidium. Mind-clouding is Dominatio or Illusio. Dispelling of one's scent can be Mutatio or Excidium, depending if you're supressing or replacing it with another scent.
4a. Ah, so the 8 schools are not meant to cover everything. Thanks, now I have a better grasp of the setting.
I think given the explanations 1 and 2, I'll ditch the lie detection specialisation (but keep Insight d8), spend one d10 on shapeshifting (not sure when it would be useful mechanically, but it's a big part of the concept . . . conceptually, so I might as well try choosing it mechanically), and the other d10 on some bunch of magical capability (almost surely the first steps of the two eloquence schools, not sure about the third; that's assuming I'm to follow the 1+2 schema as was offered to others).