Non B Visa Extension (first) -- Help Please

i got my single entry non b visa and it expires nov. 8. i also have my work permit already. my next move would be to apply for extension.

some of my friends said i would probably be getting a 30-day under consideration stamp the first time. does that mean i would get 30 days on top of the 90 days (i.e. dec. 7 expiry)? or they count 30 days from the day of application?

another question - with all the new regulations implemented now, what are the chances i could get the one-year extension on my second try (before dec.7)? i am flying home on dec 22 and would like to know if i should cut short my vacation (initially intended to be until jan 14) to go to immigration and extend again.

help me please.