question Do domain hacks infringe trademark?

It depends on the trademark and the domain hack. You could have a site about the Amazon river at Amaz.on. You could sell the fruit Apples at App.le. But you'd likely have a problem with Microso.ft.

Yes it does and the Trademark Holder can file a dispute over a domain hack as well, if no legitimate use is otherwise possible, in terms of the examples given above by Mr. Draco. Last year InstantDomains, filed INDRP over InstantDoma.in and were successful, as there was enough evidence as to lack of legitimate interests and bad faith.