It sounds as if the speaker is talking to an enemy whom he has wished to kill for a long time. "Auld aquaintance" can be translated to "old aquaintance", or someone you have known for a long time but probably is not a friend. So, the speaker is asking himself if he should simply forget this person, but answers saying "No," and that the question doesn't even actually need a response because the answer is so obviously "no".

Thank you:)

right gude = right good or very good; willy waught = warming drink (whisky?). Another more questions on 18th century Scots dialect ? Robert Burns is my favourite poet. Try reading 'For a'that' http://www.robertburns.org/works/496.shtml

Thank you! I have trouble with what you said :) I really didn't get it! 'And we’ll tak a right gude-willy waught'?!

Yes it's a rhetorical question, with the rhetorical answer being no. It means Should old friends be forgotten, just because it was long ago? I thought you would have had more trouble with 'And we’ll tak a right gude-willy waught'.