Briefly:
Lead runner = first support runner to go through the gap on the outside of the ball player, often runs an unders line (angled back towards the PTB)
Liam Farrell runs this line and role for wigan
Sweep Runner = the second runner who takes the ball from the ball player,behind the lead runner. runs a slightly lateral line across field before straightening up to draw a defender and either passing to another lead runner or another sweep runner.
Blake Green ran this line for Wigan with Sam Tomkins often being the 2nd sweep.
Inside shoulder = almost always the defenders shoulder closest to the PTB
Outside shoulder = almost always the defenders shoulder furthest away from the PTB
I'm not going to try and explain when an inside/outside shoulder isn't as described above because it's going to sound complicated and would confuse everything.