Same footer in multiple pages

'I would surely appreciate a response back'.

I'm sure the contributors that provided their time and suggestions would also appreciate a response back. It can't be that important, I assume, 2 days have passed now since you posted.

By default, all browsers add their own margins and padding to HTML elements.  To overcome this, you would need to zero out margins and padding in your stylesheet with CSS code. 

Example:

body, nav, header, img {margin:0; padding:0}

"keep the header and footer the same size and look on multiple pages."

It's impossible to predict what size devices and browser settings your end users have.  Height is determined by content.  So where your footer lands will vary on long and short pages. 

The width of your headers and footers is controlled by your CSS layout.  The CSS is placed in an external stylehseet to which all your HTML documents are linked.

For consistency, I use PHP server-side includes for my sitewide headers, footers and navigation.  In order for this to work, your server must support PHP code and your parent documents (index, about, etc..) must have a .php file extension.

https://alt-web.blogspot.com/2015/07/server-side-includes-with-php.html

Dreamweaver also supports its own proprietary DW Templates and Library Items.  But neither of those work with other code editors. 

In Dreamweaver terms you can create a template: https://helpx.adobe.com/dreamweaver/user-guide.html/dreamweaver/using/creating-dreamweaver-template.ug.html

There are also a multitude of ways to do includes, they vary based on your server/technology stack: https://css-tricks.com/the-simplest-ways-to-handle-html-includes/ 

With regards to removing white space, the best way for us to help is to have you share the page in question or a sample page so we can see what is happening and evaluate the code.