Anyway hell is not as bid a concern in Judaism as in other religions. Judaism is more concern in life in this world. A Jew is supposed to do as many commandments (mitzvahs) as he can simply because G-d has asked him to do so and not for a reward or fear of punishment.
I dont think it is that true. It depends who one asks, but their are books in Judaism that talk about hell, and one would definitly be full of fear and terror if they have read a lot of it. (of how even sometimes the tinniest action would be judged).
There are Jewish scholars who studied these aspects but this is mainly philosophical and mystical study. Judaism is much more practical- The Torah, the Talmud, they deal mainly with life in this world.
As for the other part of my claim- I don't think it is the common Jewish approach to tell people "do this mitzvah or you go to hell" After all the Torah almost never provide a reason behind the commandment.
Maybe not that, but it is common and right to say that if you do this or that Avera (sin) you will suffer in hell for it (meaning you would need the purification process).
It also depends on the lecturer, and the style. Definitly more of the American style is to be overly nice and not focus on the punishments soo much. But the style of Eretz Yisrael (even if it is done outside it) Is different, and usually it has much greater spiritual and psychological impact on its listiners. It shows the seriousness of Mitzvot and Averot. And shows the greater impact of things. (for example Rabbis like Rabbi Mizrachi, get people religious after 1 lecture- peoples minds and attitudes open up, as opposed to some others- who have people coming in for years and still women wear pants, or people dont keep Shabb-t, and other things).