leperlord - you need to be extremely careful when using UK Slang/abbreviations outside of the UK.
Yes a Mate is a good friend/pal but it should only be used when in face to face with that person and certainly should not be used in/on the Forums/Boards.
And whilst the word Fag is an abbreviation for the word Cigarette to call someone a Fag is to accuse them of being Gay
But the same applies the other way round for example in American slang "patting somebody on the fanny" is another way of saying "patting them on the backside" but saying it to somebody in the UK, especially a female, will get you a good hard slap on the face, because in UK Slang the fanny is a reference to their sexual organs.
I love your username btw
I have used "mate" on social media since day one many years ago.I do not think I have said anything else when being familiar/friendly. Maybe bro, but one has to be careful with that one based on what is or how one identifies
My grandson tho, I think he was 3 or 4,in the most respectful way he called my daughter-in-law "Dude " or "bro" IE "WOW thanks dude" Or "Thanks bro".He is a character and keeps me laughing
I have heard some of my Brit family say "front Fanny" LOL. You obviously know what that is.
I absolutely love the Brits and what they do with their own language
My very Brit gramps raised me on the BBC starting in the 1960s, so all the old classics. I now as an adult have binders of BBC classics in my closet.
He used to tell me "Mate,you will never find a girl as good as an English rose" He was correct,and she tore my heart out for 11 years then left lol