Line is incoming power. Load is outgoing power. For example, imagine
a kitchen counter wall with many outlets. The line power comes from
the electrical panel (or one of the other outlets) and then the load
power goes to power the next outlet in the line. When the wires
reach the new outlet then they go into the line power for it.
Recurse.
GFCI protection is needed on each circuit in a kitchen. So, if you
have multiple outlets you can wire the first one to be GFCI and that
protects the whole series of outlets on that circuit.
Outlet orientation is notdefined. But, generally hot side (smaller
opening) is on the right hand side when outlet is vertical.