In the interest of making as much of a one-stop-shop as possible apart from collectibles, I've compiled all 28 achievements that aren't related to the two big sets of collectibles into one video.
For Alexander Goatstafsson, head up the hill nearby after doing Tony Goat. Look for a ring with some people watching goats do battle. Head into the ring and headbutt the opponent goat out of the ring (slow-mo helps). After doing this 5 times the achievement will unlock.
This achievement can be seen starting at the 04:07
mark in the video below.