Salaam & Greeting

Q: What is the ruling of hugging a friend in Islam? If I am a girl and hug my friend who is a girl too is it permissible? What about hugging your friend everyday at the time of meeting and departure?

Q: Please advise if a niece is allowed to shake hands with her uncles (mums brothers) and clarify all who are allowed or not allowed?

Q: Is it kufr to end a letter with "regards"?

Q: Please explain the severity of writing Salams, Slmz, Salam Alaykum, Slms etc instead of writing Assalamu Alaykum. People think it's no big deal when you tell them. From a scholarly point of view please elaborate why these abbreviations and versions of conveying Salam are incorrect?

Q: When a man makes salam to a woman, should he say assalamu alykum or assalamu alyka?

Q: When meeting someone after a long time is it sunnat to embrace / hug one another? Is the sunnat for ones head to go towards the right hand side, what other Sunnats have been mentioned regarding the embrace with regards to hand positions etc?

Q: What is the correct way of greeting? Assalamu alaikum or Salam alaikum or Assalam alaikum?

Q: I want to know about salaam. I heard or read in book when Nabi (Sallallahu Alayhi Wasallam) used to meet any one He use to greet him with salaam and when departing then also with salam. Is it correct if someone says Allah Haafiz or Allah ki hifazaat when departing or Sabaahul Khair? Please  give me some explanation according to Hadith. 

Q: Is it permissible in Islam for a strange man and women to make salaam?

Q: Can Salam be written in text as aa or you have to write in full?