query syntax lucene.net (in asp.net)

Question

hello, i have a question concerning the query syntax from lucene.net

1) when i'm searching for "test" it works. when i'm searchng for "test-t" there are results too, but when i'm searching for "test-t*" there are no results

i read, that the "-" stands for NOT - but how does this works in one string?? [in two strings: test -t --> test -t]

2) how does lucene.net handle an "_" ? --> filename: my_doc - how does this works? is _ a blank? or a "real" underscore?

3) is it possible that lucene.net optimize a word a little bit too much on default? --> test-t --> test - this question is very equally to the first-

thanks in advance