1. The gemara quotes a machlokes whether the pasuk of בנים אתם לה' אלקיכם applies only when they are doing רצונו של מקום or even when they are not doing the ratzon of Hashem. The gemara in Baba Basra 10a explains similar to R' Yehuda that they are only called children when they are doing the ratzon of Hashem, but when they are not doing the razton of Hashem they are called עבדים. The K'sav Sofer (Achrei Mos) explains that רצונו של מקום doesn't just mean to do mitzvos, it means to do mitzvos because it is the ratzon of Hashem. Based on this approach, the definition of אין אתם עושין רצונו של מקום means, when you are doing mitzvos but not li'shma, meaning not because it is ratzon Hashem. When they are doing the mitzvos because it is the will of Hashem they are called children, because will to for their parents out of love, for the sake of the parent. But an eved will only serve his master because he is rewarded for serving him, therefore when they are not doing ratzon Hashem, meaning they are not doing it out of love for Hashem, they are like avadim.
2. Tosafos 37b qutoes Rashi that the Jews only brought one korban pesach over the 40 years in the midbar. Tosafos has 2 approaches why; either because there was no requirement of korban pesach until they came into eretz yisroel, or that even though they were required while they were in the desert, they were mostly missing bris mila (which for health reasons they couldn't do while travelling). One way or the other, it was considered degrading for them not to have gone in since the sin of the meraglim caused them to remain in the midbar for 40 years and loose out on the opportunity to bring the korban pesach. The Maharal (Gur Aryeh) writes that it isn't necessary to say that גנותן של ישראל was the indirect cause of the meraglim. The very fact that they missed out on the mitzvah, even if it was a result of o'nes, it is still a g'nai. The Maharal continues that although mitzvos that were not yet commanded until they went into eretz yisroel were not a g'nai for not doing, the mitzvah of korban pesach was a g'nai since they were metzuva just that the אונס prevented them from doing it.