Lore wise that character is fairly inaccurate.
Gameplay wise, I would say go heavy armor and maybe even get some resto spells. Use your summoned monsters to deal damage as you tank and maintain their (enemies) attention.
Seems perfectly reasonable to me. Orcs have no qualms about the Dark-Arts. Smart to have ranged support from Fire and Storm Atronachs. Or any ranged opponent you defeat and reanimate.
Start off worshiping Malacath, and then your opportunistic nature comes in, and you see benefits from checking out the other Daedric principalities.
Alteration, Conjuration seem fine. I'd stay away from Illusion, and of course use Orcish Armour and Weapons as Pistolero pointed out.
Volendrung is an ideal warhammer for an Orc. After-all, it is gifted by your patron himself, Malacath, Prince of Vengeance.
Yes,
"The Black Arts on Trial" is an in Game Book from Oblivion. The Balmora Mages Guild has an Orsimer that is a closet Necromancer. Orsinium allowed Necromancy to be practiced on Convicted Criminals.
A Bound Battleaxe is not a bad Weapon, but Dual Wielding Bound Swords seems to level Conjuration faster in My experience. With the Mage Stone I have had a Nord get to 90 in Conjuration in the teens, and get Mastery before Level 20. This was a character that did not pay for training or spam Soul Trap on corpses. The Bound Battleaxe has to be dispelled to cast another Spell, and is only comparable to an Elven Battleaxe in damage.
MichealPK is correct in watching how Items are sold to level Speechcraft. Joining the Bards College gives access to a Speechcraft Trainer.
Yes, the beauty of Skyrim is that you can create what ever character you wish and play how ever you like. Nobody has to stick with convention here.