Do game developers get a percentage of the sales of the emoticons/backgrounds?

i think so, as placing an order it states, total price 0.03 0.01 for the seller, 0.01 for steam, 0.01 for game X..
so i would asume they do..

I think the cut is:
85% for the seller
10% for the developer
5% for Valve

buy emoticon/background
check your e-mail
if u will see same as u see when u buy trading cards - so yes, they get a percentage of the sales.

View attached image.

I think so. For some devs they get more money that way than selling the actual game, and you know which ones.

That's the reason of massive free giveaways. Game isn't selling well -> give it to bundle -> give it away for free -> make again money on cards/emoticons/backgrounds -> make new game -> repeat.

yes, that's why they give away keys for their games, it's not just to promote.