What's the difference between...
 

a mobile optimized site to one that is geared towards the iPad? Is there such a thing? And is there a difference in makeup and content between smart phones using Android and ones from the iPhone?

And is there such a thing as a site that is mobile optimized but not SEO optimized?

I would also like to inquire how difficult it would be to prepare an existing site and make it mobile optimized? Do I have to change my content (including text and other plug-ins) radically?

I think ipad can run a web page just the same as your computer but only supporting the apple friendly media formats? I think most sites redirect mobile users to mobile versions of their sites.

Comparing mobile optimization and SEO is like comparing apples and oranges. Mobile optimization is designing your site so that your pages display properly on a wide range of mobile devices. SEO is getting your site to rank well in the SERPS. Doing well with mobile optimization doesn't ensure that you will do well with SEO and vice versa.