Hello,

The bottom menu is enabled and configured in the Theme Settings > General > Mobile button navbar.

As for the space on mobile. Please deactivate all the plugins not related to the theme, switch the parent theme, and check the issue, If the problem has gone, activate the plugins one by one, checking the issue to detect which one causes the problem.

As for the third screen, just drag and drop the row with the infoboxes to the place you wish.

Best Regards