It is real dumb that the camera controls are so fast and have that nasty motion blur on them. It doesn't make me sick at all so your mileage may vary. It generally just doesn't make manually controlling the camera very useful, which for the most part is fine because its a PSP port that didn't originally have a second stick for camera controls so it has an aggressive follow camera and relies on locking onto enemies. My recommendation is to just let the camera control itself 90% of the time especially in battles using the lock-on and it won't be a big issue.
I think its the easiest of the 3, and i played them in order of release. Totally people will find a different game more difficult than the others, but none of the are WAY harder than the others.... they are all pretty comparable in difficulty I think.