Not being as experienced and knowledgable as many are on this site, I still find the subject of BDSM and submission very intense AND scary.

What level of fear do Y/you prefer?
My level of fear I assume will change as I experience more and more intermediate to extreme levels of punishment and bdsm tools.
I am hoping the level of fear present each time will keep me on the edge of begging to stop vs my DOM making me go beyond any limits I may have.

Is that fear for the implements? For the demands that will be placed on you? Fear of the Dominant?
Once I am accepted by a DOM, I never want to fear my DOM himself. But I expect to fear what my DOM will have in mind for me which I
will hope I will not know until moments before I will experience that specific implement or tool or punishment. The unknown is very much
a large part of what I want to experience as I progress in levels of pain and learning.

Are Y/you able to articulate what the fear does in your body and mind?
For me fear and not knowing makes my body feel like I am being controlled by something else that not being my own mind. I realize I am
100% submissive and have certain responsibilities and duties to my DOM. Even after the few experiences I have had, my inner self remembers vividly what I was feeling and the pain or climaxing that happened. In a quiet environment, I can close my eyes and recreate
in my mind close to the actual event and climax and almost possess the same fear inside my belly and chest and mind.

And then the bonus question: Does fear help your trust to grow? Can the sub say so about the Dominant and why? And does a sub's fear make Your trust in him/her grow, Dominant?
Because I am married and have family and job, once DOM does accept me then I will need to trust him. Giving my DOM control and dominance over me, I have no choice but to trust he will keep my marriage and job safe from finding out who I truly am and what I am.