-We're not meant to be isolated from the world, we're meant to apply our Torah learning to the way we conduct ourselves in the world.
-Those who work with the community, on its behalf, have a special level of responsibility - such that work with the community is equivalent to Torah study. (Yerushalmi Berachot 85)
-Don't separate yourself - i.e. do your best to be an active and constructive part of the community
-Don't judge 'until you come to his place' - We cannot judge people through our own eyes.
-Speech is a major focus of Yom Kippur - the bulk of the sins for which we ask forgiveness are related to speech.
'timid person' - The Rabbis speak about the scholars in the yeshivah as ba'aley tri'sin - swordsmen. Confidence in one's own reading is important, and, at the same time, we also need to practice the art of listening. See Avot 6:6, 'Torah is acquired through 48 virtues: (1) Study (2) Listening...'
'Be a 'mensch' - The word is 'man' but it means a virtuous person. Rambam writes: 'Make a habit for yourself and strive to acquire virtues.' If we fall in with the crowd, then we are guilty of the Torah's warning, 'Do not follow the majority to do evil.' Tzedek/justice is meritorious of its own right.
What does it mean to have a 'lev tov'? A good heart? -- Commentary from Mossad Ha'Rav Kook: "The one who has a good heart is also a person with a good-eye (someone who looks for the best in others) is [also] happy with what he/she has, and that person receives kind support from the goodness of others. With the goodness of heart that person is able to have a positive impact on the hearts of others...that person is good with God and with others.(Rabbenu Yonah & Rashbatz)
Your friend's property - take care of it as if it were yours. A natural extension of 'Love your fellow human being as yourself'. Why is this extra teaching needed? While things are not as important as people, we still need to make living and care for ourselves, family members, & friends. We show good faith by helping others and hopefully they will show similar good faith.
'For the sake of heaven' - Whatever it is that we do, let is be for the sake of heaven. R. Alexander Ziskind of Horodna: All our actions have the potential to 'please' God if we do them with the proper intention - that we should point both our yetzer tov and yetzer ha'ra to heaven - is this even possible?
Not free to desist - So many challenges arise that may be obstacles to doing mitzvoth - we continue to strive even though our actions may never be completed. We feel frustrated without fulfillment. Rashbatz: God is not concerned with completion; rather, God is concerned when we give up on our efforts.