Okay, so you got a 5.0 on the essay even though you only thought of 2 main flaws and you didn't have time to go back and proof it. I think we can safely assume that you're fine on the essay.

All you need to do there is do the essay on practice tests so that you're practicing the full mental stamina aspect.
I was dreading the MSR, my weakest link and I could make nothing out of it and had to spend too much time.
Next time, guess quickly and spend that time elsewhere. You can easily guess randomly on 3 IR questions (up to 4, really) and still get a good-enough score (including getting some wrong that you did try to answer).
In a TA prob I did 2 part Qs rightly but cudn't find the 3rd one and spent little too much time
For the multi-part questions, I do recommend reading through all of the parts before starting to solve the first one. If you realize up front that you don't know how to address one part, then this one turns into a "guess randomly and move on" problem.
Next CR, CR, CR, CR - one was very big and consumed lot of my time.
Do you know what I'm going to say about that?
Skip! Most of the time, we really can tell within about 30 seconds that something is awful. Skip it. (well, guess - obviously, you can't skip.)
This was an easy RC with 3 Qs and I tried to save some time
What am I going to say here?
I'm asking you this because I want you to start being able to analyze this for yourself. So think about that before you keep reading.
Never try to save time on stuff you think is easy. That doesn't mean you need to use the full average time. But don't rush yourself; do whatever is normal for you. When you rush, all you do is give yourself a chance to make a careless mistake. If you'd cut yourself off on that hard CR from earlier, you wouldn't have felt the need to rush here.
Before I keep going, think about what you would tell me if I said, "Okay, Binit. What went wrong on verbal? What do you need to fix for next time?"
Starting with IR. You blew a lot of mental energy on a section and only ended up getting a 3 anyway. Next time, you're going to aim for a 5 and you're going to do a better job of knowing when to bail.
Quant. You're going to go for 50 again. You're going to make sure that you are NOT solving anything that's going to drain you for verbal. You don't need a 51; you've got to get verbal up.
Verbal. Better decision-making! (Sensing a theme?

You drove yourself into the ground, mentally. Next time, you are going to start verbal with more mental energy (because of the changes you're going to make on IR and quant), plus you are going to let go on more questions / not wait so long into the section for the very hardest RC. You can guess randomly on 6-7 questions AND get a bunch more wrong and still get a good score.
Re-write your verbal debrief but, this time, frame it as what you want to do differently next time. (Use my comments above as a guide.) Then tell me what you think you need to do in practice to get your brain to the point that it's implementing the right decision-making mindset.