Whosoever meets the minimum passing marks criteria, as set by sbp for shortlisting (75 marks in test and 65% in each section was the bench mark last year) will definitely be called for GD and interview. Need not to mention that candidate must be otherwise eligible for applying.

Well, i also gave test without any formal preparation last year.. test was like any other NTS test made on GAT pattern. The only addition was of General Knowledge section for which one should keep eye on current national and international news hilights. Moreover do prepare Gelneral Knowledge of country's capitals & currencies, international otganizations, international and national supports events, remarkable anniversaries, global awards and prizes and their most recent winners from some who is who nd what is what type book.
For GAT type questions (english, analytical reasoning and quantitative section)..do prepare from dogars test masters book suggested on nts website.
I had an advantage of banking background..thats why if there were any banking related questions (which were very few in number) they did not pose any problem to me.

Dear its too early to discuss that here.
If you are so curious about it then please read the tgread of sbots 18th batch at this forum.