Some comments -
(a) can't help with the reference unless I do the same research you can do .. when you find it, perhaps you can cite a link for the rest of us ?
(b) you will need to refer to the relevant State requirements for the specific rules
(b) normal requirement for multis (I presume you are talking heavy turboprop ?) is to cover the OEI case or else you will have route distance limitations
(c) for OEI planning, nett is whence the numbers need to come - otherwise we wouldn't worry about nett for takeoff and such.