When a star meets a Black hole , will the star and all of its particles be absorbed instantly ?

It depends on the "impact parameter" (distance of closest approach) and to some extent on the spin of the Black Hole.

If the Black Hole is very massive, and the impact parameter is small, then the star can just be swallowed up.
If the Black Hole is not massive, it will be much smaller than the star and will "disrupt" the star, perhaps sending some of the material from the star away from the Black Hole --- this can be very bright.

No... the black hole will likely 'feed' off the star, pulling material from it as they orbit about each other. If a LOT of material is pulled off the star at once, then some of it is accelerated - and shot away in two great jets on opposite sides of each other.

Remember, time is relative, so when referring to time you have to define what that time is relative to ...

From the perspective of someone far away, the star will never cross the event horizon into the black hole.

From the perspective of various pieces of the star themselves, depending on the distribution of the star, each piece will take a different amount of time to cross the event horizon. The tidal forces (differences in the acceleration rates) will be quite extreme for normal stellar type black holes, so there will be rather dramatic difference in acceleration rates between the parts of the star that are farthest and closest to the event horizon. So, no, it is not instantly from any time perspective.

Even it the star comes close enough to fall into the BH, it still takes some time, at least a few seconds. Most times, the star becomes a ring around the BH, and then it can take many days or more to fall in.

Not necessarily. Most Black Holes are surrounded by stars caught in it's gravitational pull in a huge ring. The center of most galaxies are black holes.

No - black holes are notoriously messy eaters. Less than 10% of the star would get past the event horizon.

Black holes consume everything in their way - in the vicinity. Gravity pulls anything and everything in when it is within a certain range.

No, stars are really big.
Our sun is over four light seconds wide.
Nothing can happen "instantaneously" when it is that big.

If a star "meets" a black hole,ie it reaches the event horizon, it will be pulled inside quite quickly. If it is nearby but a bit distant, tidal forces will slow it and pull it closer until it reaches the event horizon or until it is ripped apart and forms part of the accretion disc

Yes