Q: When importing multiple photos into Photo how due you add tags, keywords and titles to all the photos importing at that time?

Go to the Last Import smart album, select all photos and create a new album with them.  Open that album, select the photo you want to have the same keywords, type Command+K to bring up the Keyword pane and add keywords to all selected photos at the same time.

There are several Apple scripts for adding titles to selected photos.  They can be found in Photos for Mac User Tips.  There is also a script for adding the same Description to multiple photos.

Moments in Photos are the new Events, i.e. groupings of photos sorted by date taken.

When the iPhoto Library was first migrated to Photos there was a folder created in the sidebar titled iPhoto Events and all migrated iPhoto Events (which are now Moments) are represented by an album in that folder. To open the sidebar if it's not already open use the Option+Command+S key combination.

There's a way to simulate events in Photos.

When new photos are imported into the Photos library go to the Last Import smart album, select all the photos and use the File ➙ New Album menu option or use the key combination Command+N.  Name it as desired.  It will appear just above the iPhoto Events folder where you can drag it into the iPhoto Events folder

 

When you click on the iPhoto Events folder you'll get a simulated iPhoto Events window.

The downside to the simulation is that the Albums/Events can only be sorted automatically by Title. But they can also be sorted manually, either in the sidebar or in the folder's window at the right.

Ask Apple for more sorting options in Photos via https://www.apple.com/feedback/photos.html.