I hope you're great. Answers to your questions:
1. Pentaho Data Integration tool gives you the opportunity to import 4 types of components to the CMDB: Computer System, OS, Processors and LAN End Points . That if you're using FootPrints. Another way of uploading data to the CMDB would be uploading a csv file to it. This would be the first step, consider the csv as the parent, because you probably have all the data on the file. Then when you upload the info of the FootPrints te system will create (by pentaho) a unique identifier so it will add the previous info with the new one (reconciliation of some sort).
2. If you use Pentaho you can schedule jobs to have the information synchronized. Otherwise the best practice will tell you that every change that you intend to do any change in the CMDB has to go through Change Management (tasks,etc). Pentao also gives you the opportunity to creat new jobs and transformations in case you need to import more data into your CMDB from FootPrints.
3. Once the integration if sucessful, there are two buttons that will automatically appear on your screen when you look for a CI.
This one, will provide you with Quick CI information (The same information you would get if you right-click the device on the Asset Core console - check connection, file transfer, inventory details, etc).
You should go through all your roles and profiles to adjust them according to the needs of your org when it comes to managing the CMDB.
Have a good day,
The answers provided were really helpful!
Wish you a good day.