Here: Market Samurai Program, free trial for 15 days or so and Adwords tool from Google and let me know if you need any help, I do SEO and can rank for many keywords.
No it is not a VAST process....use the aforementioned Google Keywords Tool....is takes 5 minutes https://adwords.google.com/select/KeywordToolExternal
Research is the most important item in the Keyword stage. You need to pick a few niche keywords that you want to target and take a look at the top domains for those keywords. Those domains are there for a reason and the proper research should be done on them.
You can use the tool already mentioned here Google Adwords, it is by far one of the best ones. There are other pretty good tools online, just do a search in Google, Yahoo or Bing and you will notice quite a few options.
Just download Microsoft's ad intelligence, it is an excel add on and tells exact searches per month in Bing.