1.Stats: Should Darmanitan get a stat boost, Evolution, Mega Evolution or nothing?
Darmanitan Standard can get at most +60 BST to match Zen Mode.
Darmanitan can get an evolution, though Zen Mode already works as one.
Species with form changes generally do not get Megas.
2.Should Darmanitan get more abilities?
Yes. Darmanitan only has two Abilities and needs another. Some options would be Iron Fist, Drought, Flame Body, Reckless.
3.Should Darmanitan get more moves?
Slack Off and Nasty Plot are obvious options. Psycho Cut and Psychic Fangs are also options.
4.What additional typing Darmanitan can have?
Fighting, Ground, Normal and Rock are options.