Probably the best move you can make is to cease seeking to prethink answers.
For any given CR question, there are many many ways to correctly answer that question, and the correct answer will often be one that you are very unlikely to think of. So, seeking to prethink is a waste of time. Thus, prethinking is taking up time and contributing to the issue you are having with time spent per question.
Even worse, once you come up with a prethought answer, you can waste EVEN MORE TIME in looking for a choice that matches that answer.
Meanwhile, your third point, "Sometimes I am not able to fully comprehend what the answer choices are saying. The ticking timer adds more pressure and stress." is what you need to focus on to improve your CR performance. The only way you will reliably answer CR questions correctly is by developing skill in understanding what each choice is saying and what the effect of each choice is.
Does the choice weaken, strengthen, explain, support a conclusion, define a degree? What does it do?
To develop that skill, you need to practice CR untimed, analyzing each choice as if each choice were itself a question. Don't select an answer choice until you have analyzed and fully understood every choice. Yes, doing so will sometimes take 15 minutes or more for one question, but doing that type of analysis is the only way you will develop skill.
For some more CR tips, you could read the following post.
GMAT Critical Reasoning: 8 Essential Tips