when the engine if off you cannot by any chance engage D - the lever will sit at D all day long but with no oil pressure your clutch packs will not move - hence remain in neutral - and you can push it to whatever speed you want - the torque convertor will not spin the engine because its not full of oil and the clutch packs are not at bite point because the oil pump of the transmission is not spinning. - you cant push start an automatic car its simple as that...
For the others - always make together a simple maintenance toolkit to carry with you on a long journey.. throw in a dissy cap and rotor too if you can.. other than that a set of jumper cables a tow rope and a piece of wire always come in handy.
I always like to see the charging voltage of the alternator on the dash - its not a very expensive meter to hookup - but its a precaution of failure before it happens. Also another good meter is the engine oil pressure and temperature one - if automatic the transmission temperature also.
first aid kit is always welcome my first aid kit box came original with my VW - Ive put bandage, instant bandage, ointment, toothpaste, tape, instant stiches (skinweld) and some heavy duty disinfectant, a pair of small tongs and a pair of small scissors - original VW lol