But we could not understand your issue. Can you please share us your site url and screenshot of the issue. So that we can fix it?
For second question yes plugin can be customized to add other information. It can be done with hooks. If you want us to make customization then you can check http://wptravel.io/hire-our-customizer/ this page.
We have checked the issue regarding the departure dates selection in the provided screenshots.
By inspection of the issue, it seems like the issues have been caused by JS conflict in your website. To debug the issue further, please check your debug console for any JS issues in the trip single page.
If the issues are not found/resolved, please provide us your website login credentials so that we can check, debug and resolve the issues accordingly.