Because torque comes from pressure and the system supplies more as the load rises. An electric motor bogs down and overheats when a large barrel meets rebar; a hydraulic drill holds its speed through the reinforcement rather than stalling and needing to be restarted in the cut.

Electric drills are adequate up to moderate diameters, and beyond that the hydraulic machine becomes not merely faster but the practical option. The crossover depends on the concrete, the reinforcement and how continuously the work is done, so it is worth assessing against the actual job.

It removes the electrical hazard from a process that involves water by design, which is a real advantage. Water and electricity around an operator holding a machine is a combination worth avoiding, and hydraulics avoids it without giving up power.

Yes - there is no exhaust, so hydraulic core drills work indoors and in confined spaces where a petrol unit could not be used. The power pack itself needs siting appropriately, and an electric pack keeps the whole operation exhaust-free.

Rigidly, by anchor bolt, vacuum base or jack against a fixed surface. Any movement during drilling binds the barrel and destroys diamond segments quickly. Vacuum bases need a smooth, sound, non-porous surface to hold, and should not be trusted on rough or friable concrete.

On wet drilling, yes. It cools the crown, flushes out the slurry that would otherwise glaze the segments and stop them cutting, and keeps dust down. Running short of water is one of the quickest ways to ruin an expensive barrel.

The load spikes and something has to give - the rig moves, segments break, or the operator loses control. Hydraulic drills tolerate the torque spike better than electric ones, but the answer is a rigid setup and steady feed rather than relying on the machine to survive it.