Minecraft – How to teleport 2 blocks in front of an armor stand with a custom name

You cannot use relative values for changing NBTData unfortunately. Only having the head turn would take 360 command blocks, one for each rotation degree.

Having the whole stand turn is easy though, as /tp can change rotation of an entire entity, and accepts relative values. Try something like this on a clock:

/tp @e[type=ArmorStand,r=10] ~ ~ ~ ~1 ~

Unfortunately, this cannot be done with a single ArmorStand. All of the limbs pivot around pre-determined points; you can see this more easily with an ArmorStand positioning tool.

You could however position two ArmorStands in a way such that the legs of one are paired with the body/arms of another, like this:

ArmorStand for body:

/summon ArmorStand ~ ~ ~1 {NoBasePlate:1b,ShowArms:1b,Pose:{Body:[278f,0f,0f],Head:[317f,0f,0f],LeftArm:[270f,0f,0f],RightArm:[270f,0f,0f]}}

ArmorStand for legs:

/summon ArmorStand ~ ~ ~2 {NoBasePlate:1b,Pose:{Body:[180f,0f,0f],LeftLeg:[270f,0f,0f],RightLeg:[270f,0f,0f]}}

Dress them up, give Invisible:1b and NoGravity:1b to them, and then use /tp to teleport them into place: