I love the concept, Dr. Strange was one of my first super heroes to read a comic about. Would love to know how you intend to do the Eye of Agamotto.

1. I would suggest Warlock for first level; then dive into Sorcerer for a level for the AC boost. Then back to Warlock for another 2 levels. Finally, finish up with Sorcerer. So it winds up being WSWWS+. That first level will scream by pretty quick (one, maybe two sessions). You do delay 2nd level spell slots along with invocations by one level this way, so that's something to consider. Of the choices presented for order of classes, I'd say go with WWWS+. Using a feat to get eldritch blast when you know you'll get it for free in a level feels like a wasted feat usage to me. Plus it leaves that first level feat free for magic initiate (see answer to 3).

2. Dissonant Whispers I think is the better choice damage wise. It starts at 3d6 and will scale to 11d6 if you cast it using a 9th level sorcerer spell slot. I personally would say that outweighs the disadvantage that Vicious Mockery forces on a failed save. Plus, you can get this at first level, as Vicious Mockery can't be taken until 3rd level using your tome. Another option would be to get both spells, as the cantrip may have more opportunities for usage, being at-will versus limited by spell slots.

3. Take Magic Initiate as your first level feat and choose cleric as the class to get the cantrips, and first level spell from. Take sacred flame this way, gaining your radiant damage at first level. Also, you could pick shield of faith as your first level spell to be similar thematically to the shield discs Dr. Strange summons for protection. Another benefit of Shield of Faith is that it has no increase for higher spell slots, and the 1st level spell gained by MI will always be cast as if from a 1st level slot.

Yes.

The actual rules for this are oddly worded, but the notation is pretty simple.

In general, there are two formats for "things that increase your AC." The most common format is the one attached to armor:

[your AC equals] 11 + Dex modifier

or Draconic Resilience:

your AC equals 13 + your Dexterity modifier.

Note that there is no "plus" at the beginning of the formula. These items set your AC to a specific value.

The other format is that used by shields and class features that increase your AC above its base value:

Defensive fighting style:

You gain a +1 bonus to AC.

Or a shield:

Wielding a shield increases your AC by 2.

These are phrased in terms of increasing, rather than setting your AC. They are preceded by the phrase "increases" or a plus sign.

So, it's pretty simple. You get one thing that sets your AC, and any number of things that modify it (except where restricted by other rules, like the rules stating you can only use one shield).

A fighter could very easily have an AC like this:

[15 + Dex Mod] (half-plate) [+2] (shield) [+1] (defensive fighting style)

For a total AC of 18 + Dex Mod.

But he couldn't add a chain shirt to increase his AC, because both that and the half-plate set his AC to a fixed value.

The same applies to Draconic Resilience. You can stack it with a shield, because a shield increases AC. And you can further stack on the Shield spell, giving you a (temporary) total of [13 + Dex Mod] [+2] [+5], or 20 + Dex Mod.

But you can't combine Draconic Resilience with Mage Armor, because both Mage Armor and Draconic Resilience are trying to set your AC to a fixed value.

Some things Draconic Resilience stacks with:

• Shields

• Shield spell

Some things it does not:

• Plate

• Mage Armor spell

• Barbarian Unarmored Defense class feature

RAW

The rules for AC are on page 14 of the Player's Handbook, or page 9 of the Basic Rules.

The relevant part is this:

Without armor or a shield, your character’s AC equals 10 + his or her Dexterity modifier. If your character wears armor, carries a shield, or both, calculate your AC using the rules in chapter 5. Record your AC on your character sheet.

[...]

Some spells and class features give you a different way to calculate your AC. If you have multiple features that give you different ways to calculate your AC, you choose which one to use.

The rules called out above appear to be these:

Wielding a shield increases your Armor Class by 2. You can benefit from only one shield at a time.

If you wear light armor, you add your Dexterity modifier to the base number from your armor type to determine your Armor Class.

(and so on, for each type of armor)

The rules are sloppy here. Technically, they don't give you a calculation for AC when wielding a shield and no armor. And they never explicitly call out what is or is not a "way to calculate your AC."

With that said, we can use examples to build the intent of the designers.

It's pretty clear that you don't have to choose between a shield and plate. It's also pretty clear that a shield shouldn't set your AC to 2.

Finally, it's pretty clear that wearing a chain shirt with half plate shouldn't set your AC to 28 + 2 * Dex modifier (max 2).

It seems obvious then, that a "calculation" is something that sets your AC to a value plus other modifiers.

If something just adds on to (or increases) your AC, you continue to use whichever calculation is most favorable plus the new modifier.