Go to the backend, in that select “Setting” from “Hotel Reservation System” tab. Then you will be redirected to "Hotel General Configuration" page. In that page, scroll down to configuration, you will find Hotel Background Image, in that click on add file and select the image which you want to display.
Using the changes in the link will change the view, but you will need to make changes that are for image panel only, do not make changes that are not relevant to images panel.
The upgrade module will not clean the database, all the data created such as rooms, images, pricing, facilities, etc. will be saved.
The upgrade module will only discard the changes done in the code and add all the new features.
once you install the QloApps it creates a fontend as to provide a fully functioning hotel reservation system. To edit the frontend you can create a new theme or edit the default theme "hotel-reservation-theme"
QloApps is based on Prestashop, please follow their doc to understand how theme works.
I've successfully edited the CSS, but attempting to add a whole library is going to cause trouble. Not recommended. As far as adding drag and drop capabilities, that's unlikely to happen unless you develop the theme yourself as it requires a fundamental rework.
We are currently not using these templates. These templates were removed from Qloapps but are generated during installaion due to some issue, we have noted this issue and will be resolved in future version of QloApps.
If you want to use this module, you can get it from github as it is an opensource module from prestashop. Currently we do not provide support for this module but we will soon provide a module with similar features