For Facebook you have to create a Facebook page for your site but I wouldn't worry about that until you have your website completed.
Why don't you use Wordpress on a self-hosted website - best for SEO.
You need a facebook (fan) page so people can find you on this network, nothing to do with keywords on your website. Although you can create a link to your FB from your website.
As far as I know you don't need the whole Keyword stuff to find you on Facebook. All you need is Facebook Page. You can check the link below on how to optimize your Facebook Fan Page.
It seems you are very new to website thing. After you building your website you need to do some marketing so that it gets decent traffic and people know about your website. My suggestion will be to opt for SEO as it is most effective and long term strategy to get traffic to your website.
It depends on the website builder. Ultimatewb is great for photography websites and it has a built-in seo tool.
Please picture me as an alien who just arrived here and was just recently taught what the internet is; as I speak and specially while answering, please.
I want to build a photography website.
I can use a website builder to do it most easily (e.g., Weebly, Wix, etc.)
But can I still do the whole "keywords" thing so that people find me more easily on facebook?? I know nothing so no big words if you don't mind. Thank you.