I think if there is already a good guide,It's ok to use it . We,as users, need to help the others and it doesn't change if they are our words or guides posted on other sites
They do! When enrolled in signature campaign,you aren't getting paid to copy-paste articles.Are you ? Moreover,forum executes strict Plagiarism Policy. (You might just be banned for the above post)
If you wanted to use that post anyway,you can just stick it up inside the [ "quotes "] ? Or least given credits for the source.