Hi,
First of all, sorry for the delayed response. Support crew is on summer vacation thus it causes some delay on answering question on Forum.
You can completely disable the "mobile layout" from Joomla Backend >> Template Settings.
Turning off the responsiveness on specific resolution is not an easy task to handle. You need to open the CSS files and find the CSS rules (for the resolution you want to disable the responsiveness) and delete them. It is very much time consuming process. There is an easy way to it, but it requires some custom JavaScript coding, we don't provide free support for custom coding modifications.
About your other inqueries (such as, having 2x2 grids instead of 1x4 grid) also require custom modifications and unfortunately we don't provide free support for custom coding modifications.
Regards.
Support