how were temperatures distributed across the protoplanetary disk that formed our solar system?

Answer 1

Radially symmetrical (that is, the same in all directions), and hotter toward the center, cooler toward the edge.

Answer 2

Just as it is today, the center would be the hottest part of the protoplanetary disk due to gravitational energy being stronger at the center and heating up the gas that became our sun. The farther you go from the center the colder the disk would be.