Meaning of Islamic words

Q: I read in a kitaab it is permissible to colour the hair with mehandi and katam, what is katam in english?

Q: How can we tell the difference between the whispering of shaitaan and the "whispering" (or inclinations, impulses?) of the nafs (human soul, ego, mind)?

Q: I want to know about pride in our actions and in heart. What exactly it is and how to make istaghfaar and please tell me any easy dua for it. Can we read the last part of third kalima?

Q: What is the difference between haraam and halaal?

Q: This is with regards to saying Jazaakumullah khair. One of my beloved teachers told us that it is preferable to say: Jazaakumullah khair i.e. plural form instead of Jazaakallah khair or Jazaakillah khair. Kindly explain me with acceptable evidence if it is correct to do so as my friends are not accepting this.

Q: What do you mean by makrooh?

Q: Can you please tell me in detail what are usool and furoo' in usoolul fiqh?

Q: I want to know what is the difference between gunaah, khataa, laghzish, kotaahi and kusoor?

Q: Please give me the complete definition of Makrooh Tahreemi?

Q: Can you please explain the term mustahab. I know it means preferable but I don't fully understand the term.