Regarding adding surface pressures, it should be equivalent to the "Face load" boundary conditions, if you have a pressure P [N/m2] you would for example enter [-nx*P, -ny*P, -nz*P] for x, y, and z-directions where "nx_i" is the outward poiting normal in x_i-direction.
For a temperature gradient it depends a bit how its defined? If you have an analytical expression you can enter it directly in "T" coefficient edit field. However, if you have it as tabular data you can use the '
finterpn' expression as done in this example
https://featool.com/doc/Heat_Transfer_08_heat_transfer6 .