Q : Is it possible to change desktop resolution width?

A : Yes, Appearance > Theme Options > Layout > Content / Page / Post : Page Postion / Layout : Default Width.

Q : Are there page positioning and sidebar options?

A : Sure, Appearance > Theme Options > Layout > Content / Page / Post has all the required options. Besides, all those option also available as individually for each page. Please see; https://contrast.freevision.me/help/metabox/page-options/