I'm going to guess no on your first question unless you have conductors of different voltage systems.Meaning 277/120 in the same LB. Read 210.5{neutrals included 200.6(D)}
Neutrals should be white unless they're no #6 or larger, which then the only need to be identified at termination points 200.6(B).

Jesus may have been a capenter,but God was an electrician.Genesis1:3