I am eager to understand these topics clearly
Why? Judging by your post history, you seem very concerned with
Activity,
Merit,
Reputation and
DefaultTrust.
You should read more, and post less. All your questions could easily have been answered that way.
You've never left any feedback, you don't know what a Trust list is, and you clearly shouldn't worry about Newbies reaching DT. Newbies shouldn't be on DT in the first place.
Build Up reputation gain the trust of others members
I disagree. Building up a reputation shouldn't be your goal, it should at best be a "side effect" of your actions.
no newbie in the entire history got the trust of DT to include then on their list as early as few weeks.
If only that was true! In reality, all it takes is to bid on an auction, leave the seller positive feedback, and without risking anything and without any other feedback, you're on DT2: