Diesels are fairly simple beasts. They like clean air, clean fuel & clean oil.
You are wise to start with a baseline. Clean filters all around, fresh oil, a check of all hoses, check for seepage around injectors & fuel pump, check for seepage at all gaskets. Getting access does not look easy. My experience comes from diesels in boats. Most of them seem easier than a DP. Doing the routine checks seem easy enough but any real work, like getting to the starter in a DP, horrors.
Bottom line, if you are comfortable with a gas engine adapting to maintaining a diesel is no great mystery.