The simulator is the same for barbs or active players just make sure you scout the wall and find out the wall level and add that into your simulator.
As for farms depends on what level of the world you are. Start up with barbs having no walls you can send as little as one LC, later on when the walls grow your ether gonna wanna smash them of send 15-25 LC.
But this is also opinion, you can find what best fits your farming area as far as how many LC to send.
erm tbis is from memory but somay like
1 lc always survives 0 wall
1lc survives lvl 1 wall 50 percent of the time
2 lc survive a lvl 1 wall always and has sum chance of dying on a lvl 2 wall
8 lc are needed to survive a lvl 2 wall every time
after that no idea i keep walls low
