Can someone explain to me how the DT2 works?
You're included in DT2 if someone from DT1 puts you in their trust list.
I am guessing Depth 0 is for myself and default trust only
Depth 0 also includes the people that you trust or distrust. You can put a ~ beside their name if you choose not to trust them, for example ~ranochigo. Depending on your depth, if you put some users into your trust list, the people whom they trust would also appear under the trusted feedback.
But who are these people in the default trust? Dt1 people? or both dt1 and dt2?
DT1.
some of these names are stricken out.
Why? how does one get their names struck out? or how to prevent it from getting struck?
One more thing, what are those numbers in the brackets? What does it mean? High good? or low good?
If they're struck out, that means that their DT peers has chosen not to trust them and decided to exclude them from their trust list. The number indicates their DT strength.
Here's a better and more comprehensive explanation:
https://bitcointalk.org/index.php?topic=5072734.0. More usefull guides are colllated in the thread here.:
https://bitcointalk.org/index.php?topic=4928968.0.