Enfold Site Width Confirmation

Please see the screen shots here show site widths I have researched using Firebug:

(I made sure to keep this page very simple. Just a series of screen shots. Most have captions.)

With Firebug:
I can see that the actual full width for BertaArt.com is 1140 pixels wide.

With a sidebar, the content piece is 782 pixels wide.

An image is 770 pixels wide.

For the Enfold settings, as you can see in the first 2 screenshots:
For content/sidebar I put 73%/27%

In settings, I put 1240 pixels for maximum container width but I should probably change this to 1140 which is the actual container width?

Can you please just confirm that I have deciphered what the actual widths are.

I want to use a sidebar on all pages and posts except for the Home Page.

I know that I can put in larger images because the site is set for “stretched content” but I am trying to do as little of that as possible for the sake of site speed.