This is usually suggested as coming from the Dutch boedel, “inheritance, household effects; possessions”. But it’s uncertain whether it’s the same word as the one in the whole kit and boodle. Some writers suggest the latter comes from the English buddle, meaning a bundle or bunch (closely connected with bindle, as in the North American bindlestiff for a tramp). As kit here means one’s equipment, to put the two together in the sense of everything that one has, equipment and personal possessions, seems reasonable.

It means, everything.

The whole nine yards

that the whole thing is done, the entire subject is covered,