You can have a look this site: http://www.codegrape.com/category/themes
Yes. Definitely.
HTML-CSS and PHP knowledge is required to create a wp theme.
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It seems well enough. But, I suggest you to make it responsive.
You need to create HTML5 elements manually by JS: document.createElement("header"); document.createElement("footer");
You can put jQuery-HTML5 slideshow after the main navigation generally.
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You just need to change some CSS styles according to resolution. But, it can be a hard work, if your site isn't CSS3.
I suggest you to learn PHP.
I suggest you to use for HTML5-CSS3 technologies. Otherwise, your website code can't pass the validation. Then, your site can't be read by search...
You can redirect one domain to other one. But, you need to have the privilage of server to login via SSH.
Separate names with a comma.