Promote my website please

Was recently asked ‘can you put together an SEO package for me for my new website?’ my answer below highlights the fact you need to take a step backwards and look at the big picture when planning to build / promote a website.
It would be very easy to say yes we can SEO it and could make improvements but the site in its current form is probably not fit for purpose. We dont really want to polish a rusty car here, we need to design and service a new car for you.
Assuming this website is for a worldwide audience there are some fundamental design / usability / SEO problems that would ideally need this website to be redesigned on a content management system that is responsive using a .com domain, if this is done correctly it will improve the usability and SEO and future proof the site to allow it to be easily updated / improved going forward by yourself.
Therefore I would propose buying a .com domain so that we can get worldwide visibility to the site then re-creating all the content / pages / sections in a search engine friendly way, after you approved the redesign we could then re-direct all the old to the new pages then perform all the standard SEO tasks required to get us to the starting block. The good news is that if you are pretty open with the design it would be easy to design / create a ‘text’ only / informational site. So the design element of the site would be minimal and we can concentrate on the development and SEO.
To start this we would need domain registration info to enable the redirects to be put in place and your thoughts on my proposal above.