Affiliate Marketing Secrets

Hello All.
Hope some of you will be able to give me some straight answers for these questions. I’ve done my own little ‘crash course’ into SEO and Internet Marketing this week. I’m confident (ish) on most areas, but have stumbled on some questions which I need to clarify. (Sorry if some of these sound stupid) but here goes :
1.) Do Follow and No Follow Links. I know how to see if a website is ‘Do follow’ or ‘No follow’ but when gaining backlinks, do I always have to type in either the ‘do follow’ or ‘no follow’ code? I know I should do this for commenting and my own blog, and for other blog comments, but what about article directories, guest blogging, directories etc?
2.) I understand that in theory, posting on ‘do follow’ Auto approved blogs isn’t good because it will probably be hit by scam. However, it I wrote some quality comments related to the niche and added a backlink to my own blog instead of my main page, would this be ok?
3.) How do I make my own personal blog, non- auto approved and no follow? Is it by installing the plugin Akismet?
4.) I’m currently having a website built, and I’m currently looking at Plugin’s for my WordPress blog. . My web designer hasn’t mentioned if he is going to install any Social Media plugin’s.for my blog. However on the blog page, he has included most of the social media links at the top. Do I still need to install a social media plugin, or can it be done manually without a special plugin(I’m abit worried as my designer doesn’t seem to know much about these plugin’s but has added these links for me anyway??
I appreciate your thoughts and comments.