Do chain attacks benefit from damage boosts when the art is based on position?
Arts like https://xenoblade.fandom.com/wiki/Edge_Thrust and https://xenoblade.fandom.com/wiki/Hammerhead_(XC3) inflict extra damage based on your position when attacking the enemy, that being back strike and side strike respectively.
When performing a chain attack, my units will sometimes be in the correct position to where the art that is being performed would normally receive a boost. Do these types of arts receive damage boosts based on your position during chain attacks?
Yes, they do. One of the easiest ways to test this is with an un-broken enemy, using a Side Break art (which will only trigger when you break from the side). No matter where your character is positioned, the break can trigger.