What is a good model to use to estimate membership growth over time for a dance video tutorial website?

I plan to make a website that has video tutorials for a specific style of dance (lets say like swing or salsa).

I used:

Google AdWord Keyword Tool and typed in "online dance classes" and clicked on "Search". There are apparently 5,400 monthly searches done in the United States with this exact phrase.

Is it safe to assume these monthly searches are conducted by "new" people (i.e. most people doing a search this month are different from last month)? Why or why not?

If yes, can I assume my website's membership growth rate can be modeled as a function of Google's 5400/month searches? For example, can I estimate website membership growth like:

5400 searches a month * probability somebody clicks on my website's advertisement in a Google search * probability someone becomes a member of my website = estimated # of NEW users who register every month. Does this make sense or am I oversimplifying something much more complicated and unpredictable?

If I change the search criteria in the Google AdWords Keyword Tool to "online dance class" (i.e. get rid of plurality) and click "Search" I get 4,400 monthly searches in the United States. Are these 4400 searches a subset of the plural search or are these two search phrases generating 2 disjoint search sets(i.e. there are 4400 + 5400 = 9800 monthly searches conducted in the U.S. regarding online dance classes) ?

Does it make sense to use this information to estimate a website's membership growth rate?

There is no correlation between keyword stats and real potential for growth.

Trying to do a little bit of SEO or leveraging AdWords and thinking you'll get all of that traffic is like bringing a rubber band to a gun fight.

The only real strategy is to build a quality site, push word of mouth, be patient and watchful of competition.

Depending on the term, a significant amount of the traffic could be people scraping search engines or people paid to search and click on certain sites. There's also the danger of related traffic poisoning the numbers. For all you know there could be a viral video about an online dance class or a popular TV show that they are looking for.

I would suggest looking a lot into long tail keywords. Be very specific and get as niche as possible. Focusing on dance videos as a keyword may be to broad. Using a keyword such as "breakdancing for white kids" or something else (obviously a horrible example lol) This will help get better, more targeted traffic for your site.

When someone searches for a broad term, they are given a multitude of options. When someone searches for something very specific, and you give them exactly what they are looking for, $$ You have a higher percentage of making a sale.

Hope my input helps and makes sense! Good luck!!