The best way to market is to build a plan for it. Make it measurable and make adjustments.
It would depend on the type of business you are in and the demographics of the audience you are trying to get to.
SEO is really a strategy more than anything else. Sure there are activities that need to happen, but that is all part of the strategy. There are many ways to accomplish this and make it cost effective.
It is a good way to advertise, but it should not be the only way you advertise. You need to diversify the methods in which you are marketing your business to get the best results. But the reality is that there are so many ways to market now days, which do you pick?
No, baby boomers are a huge market with lots of discretionary income. Typically they are looking to do business in traditional marketing, but usually will go to your website before making a decision.
All of those options are great options, but building a basic website with a slider is the easy part. It gets more complex when you get into the animation, functionality and purpose of your website.
Depending on how big your audience is, and how active your business is, Facebook may be a great platform to invest some money in.