regarding the framelines: It's only the illumination of the framelines, that is now done with LEDs instead of the windows of past times. The advantage is, that you also get good visible framelines in near darkness, which wasn't so easy with the M9. However, it looked cooler... at least IMHO.
High-ISO is indeed a great leap from M9 to M10. The M240 was already better that the M9, but the M10 is really usable in dark situations.
The virtual horizon is not available in the optical viewfinder. Only Fujifilm does that trick. You get it in Live-View, or in the EVF.
Regarding M10 vs. M10-P: Both are more or less the same camera, especially the sensor and thus the image-quality. The M10-P has touch-screen operation as its main technical advantage and, of course, the changed design of the body. If the touch-screen and the different design is the worth the higher price, is up to you, of course. But I don't see any good reason, to buy any-digi-leica-P over the regular ones. The difference always was too small, IMHO.