Does praying the rosary keep someone from going to hell?

Of course.  By reciting the rosary every day with care and sincerity, a person can be certain of avoiding eternal damnation.

No more than Buddhists twirling prayer drums gets them closer to Nirvana. Rituals are part of religious systems that attract people who think if they do A, B and C, they will eventually please God and get rewarded. The rosary was originally recitations of prayers to 'the Virgin' in 5 sequences, interspersed with other prayers. Twiddling rosary beads is a short-cut version. That doesn't get anybody's sins forgiven by God. All those dying without having obtained God's free pardon (by repenting and putting faith only in what Jesus did to atone for their sins) will end up in hell, even if they prayed the rosary millions of times.

No but its a sure ticket there. 

No one goes to hell or heaven dead is DEAD!

Nothing keeps you from going to places that don't exist, so no it doesn't.

Praying to God keeping your mind off of sin is a good thing it shows you have faith in Christ

Those who believe in Jesus AND Love One Another are they that will not go to Hell. Everyone else will NOT be allowed to live in His Kingdom (Heaven), sorry.