When an object enters he black hole several things happen to it, all quite catastrophic.

The temperature the object will before entering, be heated to millions of degrees as it is ripped and stretched apart in the accretion disk around the hole (assuming the hole it rotating as most do). After entering the event horizon, the remains of the object will be blasted by very high energy gamma rays that are caused by light falling in and being blueshifted by the gravity of the hole.
The mass of the object (or I should say the ripped apart remains) stays roughly the same. Some may be lost in the accretion disk outside as X-ray energy. Its mass will then be added to that of the black hole when it hits the singularity.
As an object falls in the speed increases to almost the speed of light. After the event horizon is crossed, no one really knows.
As far as time goes, it gets weird. Due to the massive warping of the spacetime, time is either stretched of compressed depending on your perspective (Einstein`s theory of Special Relativity). Viewed from a distance, a clock on the object falling in will appear to run slower and slower until it appears to stand still at the event horizon. But if you where on the object, the clock appears to run normally up until you hit the singularity.