Google is strict to duplicate contents. If you just copy and paste articles from other website to your blog, google will punish you. If you publish the same article in all of your blogs, all of them will be punished.
If you just copy and paste small amount of contents, then it will not hurt your rankings, but you should avoid to copy and paste bulk amount of articles in your blog.
Each time you create a new article, the page will be indexed in google and will be placed in search results. If you delete that page when it has a big authority in google, people will then go to an error page via google. As a result google have to re-index and sort their search results that’s why they will punish the entire site.
If you edit any articles in your blog, it will not effect on your rankings but you should not delete your older articles.
If you exchange links with other sites, it will help your site to get better rankings. But if you put lots of links in your website and all of them are different categories, google will think your blog is a link farm and they will punish your site. Exchange links with quality sites and sites which are in the same niche.
If you give links to bad neighborhood like a site which is not in your niche or if you give a link to a site related to Porn, Adult, Scam, Gambling or Link farms, then google will punish you.
If those sites link to you, it wont negatively effect on your rankings. Linking to a punished site is may also give you a ban from google.
If you spam other sites, blogs and forums with your link to build up incoming links to your site, the chances are that google will find out that this is spam and all of those could work against you. All of the incoming spam links will effect on your ranking and you may get banned from google forever.