Questions about the leaver system, account hackers, and atitude in game

Alright so my question is how many leaves does it take to get banned? one friend told me that the maximum you can leave is 2 times per day, my other friend said that the most you can leave is 2 times per week ! I have been getting confused and all, but this really stresses me out because in a lot of situations my dad needs the computer where I have to leave and when hes done the games already over because i was afk, go out and eat, and other important stuff such as doctors appointment,washroom breaks, grocery shopping, a lot of unexpected things has happened even tho i asked what we are gonna do ahead of time,

My 2nd question is something I always worried about my account getting hacked, how can I avoid key loggers? If I was a gold rank or diamond rank or challenger are there a lot of chances I can get my account hacked? And my friend has the same Username ID login as his name in League does that make it easier for hackers to hack his account?

And my final question is, what kinda offensive language if I said in game could get myself banned? And When I have reported people for insulting me saying im R*******, useless, noob cussing and insulting me a lot of them didn't seem to care at all its strange and they still continue.