You should be able to.
That's the main way I cut down on human error when making new resource entries.

which buttons do i need to press?

The same as explorer. CTRL/Shift + mouse for selection.
DELETE, CTRL+C, CTRL+V to perform actions on your selection.

When copying be sure you see 'new resource ID generated' or things will go horribly wrong. Paste it twice if you don't get it the first time round.
Also note that pasting things into other packs might result in broken links, as dependencies to other content might not be resolved correctly.

ctrl/shift for multiple lines doesnt work for me :/ would be a timesaver, but i can do without it ^^. one more thing id like to know about animations: can you reassign animations within a rig? for example making demigiants use one of their melee attack animations for spellcasting, instead of scratching their back (aka idle animation).

Originally posted by CapitaineYolo:

ctrl/shift for multiple lines doesnt work for me :/ would be a timesaver, but i can do without it ^^.

That's odd.
I tried it in the latest version on Steam - admitted, that is the Beta Patch - and it worked as expected there.

Originally posted by CapitaineYolo:

one more thing id like to know about animations: can you reassign animations within a rig? for example making demigiants use one of their melee attack animations for spellcasting, instead of scratching their back (aka idle animation).

No, you can't mod animation much for AoW3.

I also cannot choose multiple lines. Quite annoying when you wish to copy a whole stack.