Everything you've stated will work fine; the characteristic could be passed down differently though.
Firstly, the Destiny Knot does not work pre-XY anyway, but the Destiny Knot would pass down IVs from both parents, so that wouldn't work. If your Male Lapras has a high HP IV (hence getting the 'Loves to Eat' characterestic) then letting it hold the Power Weight might be a good idea.
Also, Lapras can only learn Curse through an egg move. So get your male Lapras to have the move Curse as well.
Hope I helped. :)
Source: http://www.serebii.net/pokedex-dp/131.shtml and Experience