Comments on the statements regarding VIT in fuel injection:

This is broadly correct in principle. VIT advances the injection timing as load falls so that the maximum combustion pressure (Pmax) is kept at its design maximum over a wide load range (e.g. from about 50% to 85% load). At 85% load, the Pmax is at the design maximum, and the engine operates efficiently. However, the statement that "100% power is achieved at 85% rpm" is not strictly correct: VIT keeps Pmax high, but the power is still limited by the fuel quantity and the air supply; the engine does not produce 100% power at 85% rpm unless the fuel and air allow it. The fuel saving comes from the improved thermal efficiency at part load (higher Pmax gives better conversion), not from producing full power at lower speed. So the statement is partially correct - VIT improves part-load efficiency and reduces SFOC, but it does not literally give 100% power at 85% rpm.

This is incorrect. VIT is used in alternator (auxiliary) engines even though they run at constant speed. In a constant-speed engine, the load varies (the electrical load), and VIT advances the injection timing as the load falls to keep Pmax high and improve efficiency. So VIT is possible and used in alternator engines; it is based on the load (fuel index), not the speed.

This is incorrect. The breakpoint in VIT is the load (fuel index) at which the VIT mechanism changes from advancing the injection (at part load) to retarding it (at high load) to keep Pmax at the design limit. It is the point where the injection timing is at its most advanced and Pmax is at the design maximum; it is not the point of maximum brake horsepower. The breakpoint is typically around 85% load.

This is broadly correct. The VIT system adjusts the injection timing to maintain Pmax at the design value, so it compensates for changes in the fuel (e.g. different ignition quality) that would otherwise change Pmax. However, the VIT has a limited range, and if the fuel is very different (e.g. very poor ignition quality), the VIT may not be able to fully compensate. So it can maintain Pmax over a range of fuels, but not "irrespective" of any fuel.

This is incorrect. Electronically controlled (camshaftless) engines do have VIT, but it is achieved in software: the ECU controls the injection timing directly and advances/retards it with load to keep Pmax at the optimum, which is the same function as the mechanical VIT. So electronically controlled engines have VIT (software-controlled), not a mechanical VIT device.