Guessing Factor in Item Response Theory

I'm currently trying to learn basics (nah who am i joking I'm only trying to learn the concept) of IRT since i have a high stake test (college entrance exam) coming in a few months that used IRT but i don't know the model of what they're using let's just assumed they used what majority of other exam model used.

Question from student perspective : from what i know

• If a student answer a question right they will get 1 point

• If they leave blanks or answer it wrong they will get 0 point

• after calculating 1/0 they calculate the question which one that have less people answer it correctly(harder), and the easier (all people could answer it).

• after that they merge the calculation to the existing score and range the highest to the lowest, and sort them by the score.

1. What i'd like to know is there a way / some kind of a variable that eliminate guess or merely luck on a test? (I read on Wikipedia there's a 'c' parameters but that's the parameter of the question not the individual people)

2. Should I answer the question randomly if i don't know the answer, or is it going to negate my overall probability of getting right in the test? (If not then i thought i could randomly pick and hope for the best)

3. Should I answer the toughest answer because less people will answer it making me beneficial ?

Sorry if this question not related to irt, i try to find my answer downloading bunch of pdf other research paper that have no correlation to my problem.

Any kind of suggestions or explanation, is really helpful.