The short answer is yes, to all of the above. Very high level shooters in every discipline shoot with very high levels of tension and others very high level shooters will shoot with relatively low amounts of tension and it has to do with each person's own unique needs. I shoot everything with very high levels of tension, my body will do that without tremors or other motion. I learned to do this in action shooting competition and I was decent at it, all of the top teachers I trained with and all that I am aware of advise to shoot with 100% of the tension you can muster without disturbing the sights or impeding the trigger pull and the more you shoot the more tension you can develop and the more tension you will shoot with. My son is a very good shot and he has to shoot with relatively low levels of tension because his body will not allow as much tension without involuntary motion, it can be overcome but I think it's a bit more difficult than it is for someone that can create a lot of tension. Lighter trigger weights and heavier guns tend to help people that can't create a lot of tension without involuntary motion.
Another point maybe? Very rarely (if ever) will you find a high level shooter that doesn't know exactly when the shot will break and they force the break when it needs to break. This is not to say they don't do that smoothly and absolutely they do follow all the way through the shot. The notion that you should be surprised at the shot I think contributes to a flinch, and hang on for all the comments about how wrong I am. Oh well. If I were to tell you I was going to punch you in the arm so get ready, I pull back and punch you in the arm fairly hard, you would be fully tensed, braced, and it would be relatively not an event at all. Now, I tell you I am going to punch you in the arm in the next little bit, and I wait until you aren't looking or expecting it my punch is going to have a lot more effect on you. Now, we are going to do this stupid exercise 20 times in the next hour. If you're ready for the punch each time yeah your arm is going to get sore but nothing like if you aren't ready for the 20 impacts. The other thing high level shooters do that shooters not at a high level don't understand at all is 'drive the gun' and forcing the break when the shot presents itself requires driving the gun. When you drive the gun you can remove quite a few conscious thoughts from the process and that is a good thing. Your brain is smart and it doesn't want you to experience unpleasant things, like big booms and getting smacked by a rifle LOL. Demand and command control of the entire process with as much tension as you can muster and see what happens, it might help you a lot.
Necchi has given the same advise I did in an earlier thread, having the rifle loaded or not for you 'blind' is a tremendous training tool. If you don't know whether or not it's loaded you will have to buckle down and prepare to get hit, or flinch for the whole world to see and laugh with your buddy. Drive the gun through the shot loaded or not is a learned experience, and you learn it a whole lot faster by doing this than by shooting poorly executed shot after poorly executed shot. Dryfire is a great tool as well, the more reps you can get in without getting punched by the gun the easier it will be to take the hit when you do shoot. In the end, you have to be willing to align and maintain alignment of the sights knowing your are going to get punched to be a good shot. You can also be punched audibly, double hearing protection is also a good idea at the minimum while you sort it out but 100% of the time while shooting it's a good idea.
The last thing I think you HAVE to do to be a good shooter is call your shots and even though all these things tie together I think this is the one thing you can never relax on the importance of, if you don't know exactly (within reason) where that shot landed without looking at the target you will never achieve the highest level of shooting you are capable of. If you don't know that the last shot broke slightly high and left without looking at the target you weren't in the shot, your focus was elsewhere when it needed to be on the front sight, or you would have seen that it was slightly high and left when the sight started to lift in recoil. You have to see this, there is nothing that can take it's place. When you get good at this you will find that the shot breaks when it needs to, and everything slows way way down during the shot, your shooting will elevate dramatically and it will elevate dramatically with ANY gun you pick up.
Not everyone will be and I don't think everyone can be an exceptional shooter, just like I think some people despite all of the training and desire and practice will ever be an exceptional painter of portraits, but everyone can get better at everything with training and desire and practice. I do think that everyone can be a solid shooter and among the people shooting that will put you in the upper tier for sure.
Hope this helps.