We have not come across any hadith which says that whoever makes someone get up from his seat will be deprived of his seat in Paradise! But whoever makes someone get up from a permissible place that he reached first is wronging him, and he should ask him to forgive him and not expose himself to retaliation on the Day of Resurrection when the issue will be settled with hasanaat (good deeds) and sayyi’aat (bad deeds).

Wudu before sleeping is a recommended Sunnah. If you are still is a state of Wudu from Isha or Tahajjud prayer, then you do not have to renew it.

If a non-Muslim says As-Sam ‘alaykum, you should respond by saying Wa ‘alaykum. If a non-Muslim greets you saying As-salamu ‘alaykum, the majority of scholars said that we have to return the greeting, and this is the correct view.