Yes. Having your own blog or website would definitely help in your SFI business. I can assume that you already know that SFI url's are not accepted and considered as a spam in almost all social media sites, your blog can be used as an alternative. However, you should check the SFI's TOS, before putting in any articles in your blog.
Yes, you need to have a personal website or blog site to help you out with your business in SFI. You got a control over your personal site and can post all of the marketing aids and gateways to promote SFI and Tripleclicks without any limitations as long as you abided with the site's regulations.
I understand that to be successful with SFI means generating the income you require.
There are many evidence that those which have a huge downlines in their team earn a big income here.
There are many ways to build your own SFI team, and you may start with whatever you have. If you think it is time to run your own blog or website in order to bring you closer to your goals, then do it!
To be successful in SFI definitely need to have your blog, because it gives you the opportunity to advertise and attract potential members of the PSA. Blog can take advantage and advertise it on facebook, and on the other networks. In my opinion Web site is not necessary for you to success in this business.