[Digikam-users] Help starting with digikam

[Brano]

I'm relatively new to digikam and trying to find out how to do few basic 
things (from my perspective).

Is there a way to create virtual collections similar to lightroom?
Example: I'd need my wife to review pictures and select them to few 
virtual collections i.e. "send to a friend" "print to prints" "post to web"
Then I'd go in, find the "send to friend" collection and export it to 
jpeg certain size.
"print to prints" would be exported using different export rules (less 
compression, resize 4:3)

I was unable to find similar "collection" functionality ...is anything, 
no necessary exactly same, available?
Is there a way to batch process pictures in a collection without having 
go one by one? I was not able to see any filters when doing i.e. batch 
resizing.

Lastly is there a way to have same JPG and RAW being treated as bonded 
couple?

Any hints how to accomplish these tasks highly appreciated ;)