Yep! It support Baking for most of the nodes. The golden rule is that view dependent can produce some unexpected results. Line Rendering of course don't make sense in bake.
There's two known limitation for the line rendering node. They doesn't work with Ortogonal Cameras only perspective and you need to enable Clamp and setup a good value for it to make it work trough transparent objects.
Blender 2.8 is yet under heavy development and we're following it close. There's no showstopper to port it in future until now and of course we will do our best to port it when blender 2.8 was close to release.
Lightning fast! You just need about 32 samples to make an production quality image. We provide many presets of quality that you can control in the Toonkit Settings in render panel too.
No. Since OSL shaders are CPU only it do not support GPU rendering.
No. It extend Cycles with OSL nodes and some python nodes to implement NPR features.