I was thinking for my redguard, I would do a non-armored, spellsword/nightblade hybrid (Mage-assassin with the ability to go toe-to-toe with enemies if needed). IS this possible/Viable? And IF so, what skills should I focus on first?

Yes; with dual wielding + high stamina you'll be able to power attack enemies to death before they can do enough damage. The tricky bit is dealing with ranged enemies. Use Alteration for magical armour + magic resistance; use terrain + sprint to attract them to you and then close the gap quickly.

You could always use Illusion, too. The best way to deal with a combat situation is to avoid it all together, right?

If people want to post here, can a mod Lock the other one?

and thanks for the advice.

Yes, I think it is viable. When you say unarmored you mean wearing clothes (so you can enchant them yourself) or mage-robes?

For the skills, Sneak is the most important for a night blade build. Then I would say One Handed weapons. For the magic skills, you have to think on what would you want.. ranged attacks with Destruction, or stay back and let them kill themselves with Illusion? Maybe, if you get caught, you can rely on a Summon with Conjuration. Or you can actually mix up and get Quiet Casting on Illusion, so you can revive a corpse of a guy you just slit the throat (quietly, so no one will detect you) and watch him take on his fellow comrades. If you get your playstyle somewhat planned, you can decide better with the most important skills for you.

I would advise against more than 1 crafting skill (smithing, enchanting or alchemy) because it makes you way too powerful. If that is how you like though, go ahead xD

I recently just turned my thief into a nightblade, its a fun build. I would recommend Illusion and Alteration spells.

I have not decided on the clothes/robes issue (I have kind of coded in redguard clothes and boots for the feel of it). I was thinking of having some kind of anti-dragon combat skill, and thought about Alteration for armor and magic resist. Illusion, sneak and one-handed make sense.

Yeah, the Alikir outfit (or whatever you spell it) is a good choice for RP a Redguard. You can enchant every piece of it to your liking too. Sneak+1H+Illusion is a great Nightblade combo. I actually am rocking a Dunmer Vampire right now who uses those 3 skills the most, and it's really effective!

Now, about anti-dragon skills, well, you could get Destruction, or Archery... Maybe, you could only have you 1H skill and use the Dragonbane Sword form the Blades, with Mage Armor from Alteration against dragons... You have to think what would be more fun for you... I think those 3 choices are all viable ways to take care of dragons... I'm sure other people will give other advices too, so you will have several different ways to chose from =D

Dual wielding will do a ton of damage but you cant block, so youre going to want high alteration skill to cast flesh armor spells, get passive magic defense, as well as illusion to go invisible, and use pacify/fear on enemies. Restoration is always good as well.