Yes, it's possible.

A few minor changes to the header.php file to disable the cart from showing, and then another on the single.php page — and that's it.

I believe there is a post or two in the support forum explaining the process.

No.

Market is its own theme, not a plugin.

One option you can do, is to install a new instance of Wordpress into a subfolder named "store" or something, and install the Market theme there. Then on your main site, you'd just add a new menu link to your "store" that's located in that subfolder.

If you do that, all you have to do is add your logo to your Market theme store, and modify the colors so they match your regular site.

A lot of other members use this type of setup, and are happy.

No… Currently, manual payment is not built-in standard.

If you want to utilize a manual payment option, then it can be done — but you'll have to modify some of the code in order to do it.

This post may help also.
http://www.markettheme.com/for…..-mechanism