1 and 2) These methods that you mentioned work for long tail terms, (low competition terms). RSS feeds, blog commenting, etc.. but you pretty much have to use bots to make them practical. (SEO bots)
You can probably find a free or very low cost bot option on the warrior forum warriorforum.com for a RSS posting bot also see scrapebox.com for auto or manual (white hat) blog commenting and a heck of a lot more (this is one of my favorite tools).
SEO traffic is very high quality in general and you can do a lot with it. I'll get to that in a minute.
3) Social Traffic is generally pretty unfocused unless you have a fan page for RED GIZMOS, then you would probably get fans of RED GIZMOS coming in pretty regularly. Which is super great if you sell RED GIZMOS.
4) Posting comments on forums can be a super cool way of both serving other people and getting your message out to the world. Be sure to give a lot more value to whoever is reading your post than you are asking in return, (like clicking on a link to see your stuff). More importantly it is a way to meet other like minded people who can help you.
and drum roll please.....
You forgot what is probably the most important method of all. Email Marketing, give your visitor a great bribe for giving you their email address, like a free report or video "7 SECRET OF RED GIZMOS" and get them to sign up through aweber.com (cheap and easy email service). If you treat your list right, send them links to free content on your site for the most part, you can end up with someone who will keep coming back for the rest of your life. Best yet if you get kicked off of Twitter, etc.., and Google slaps you silly you will still have some customers.
5) It is all about the learning curve, it is very easy to get overwhelmed or spend a lot of time on dead ends. If you are really serious about learning affiliate marketing you can!
You really can do this stuff with the right tools and training but it is tough starting out without help. Please check out the link below in my signature it is a great teaching program.