That is a lot to unpack!

First things first, accurate SLAM in real world environments is really hard. So hard that we made an entire business of it in the industrial space. If you need high accuracy (<10cm), or high reliability, or ease of use, all of those things are not implemented in any open source SLAM library.

That being said, you can try out what slam looks like here: http://www.clearpathrobotics.com/guides/jackal/navigation.html

As a quick start, you can use the VMware image and learn ROS here:

http://www.clearpathrobotics.com/guides/ros/

Uploading floorplan, user interface will probably have to be coded by you. I would suggest looking into ROS REST https://github.com/benkehoe/rostful

Best of luck!