I am not yet really familiar with the fifth edition, but as far as I know, it seems important to me to also consider that +2 WIS is also a boost to your save and some skills which can drastically affect your survavibility.

Instead of giving you my very own answer which may not be your depending your style of play, I will give you list of pros for each option.

Pros to +2 Wis

• +1 to perception checks means that you will less likely be surprised by a sneaky character, which makes quite a difference for a squishy character.
• +1 to save is always good to take even more at low levels... Yet it is a weak save for you, so at lvl 20 I doubt it will make a huge difference.
• +1 AC is pretty good, it ends up as a 5% miss chance which, on the long run, is better. Well, before lvl 20, enemies tend to hit significantly harder than 20 pesky damages. It won't do much better than "buffering", at best, a single attack.

Pro to +2 Con

• It gives you +20 HP so about 21 % more HP. It is a good bonus to your survivability yet it won't save you from a bruiser's beating.

  CON 12: 8 (monk) + 3.5 * 19 (average sorcerer HP roll) +20 (Con) = 94
  
  CON 14: 8 (monk) + 3.5 * 19 (average sorcerer HP roll) +40 (Con) = 114
  

• +1 to one of your strong saves, which is good and probably better on the long run, as the system seems to encourage you to be good in your area of expertise and count on friends to compensate your weaknesses.

Bonus:
As told previously, +1 CON won't net you the best result in term of sheer HP bonus, if you are really looking for a boost, for your HP, the feat 'Tough' is a better alternative.

Yes, it applies to all movements

Unarmored Movement (PHB, 78) States:

Starting at 2nd level, your speed increases by 10 feet while you are not wearing armor or wielding a shield.

It does NOT qualify as your Walking Speed (or Swimming Speed, or Flying Speed)...just Speed. This applies to all types of movements and would add additional speed to the Fly spell as well.

This is supported by Jeremy Crawford as well.

Unarmored Movement is intended to increase a monk's innate speed, including an aarakocra monk's flying speed.

He further clarifies Bonuses and Penalties that apply to Speed in general:

Bonuses/penalties to speed apply to your speeds in general, unless the text specifies walking, flying, etc

As the Unarmored Movement does not specify a specific type of speed, it applies to all.

Fly Spell specifically

Fly states (PHB, 243)

The target gains a flying speed of 60 feet for the duration.

The implication here is that you (the target) had no Fly Speed (or a lower Fly Speed) before casting and it is now a speed that you, the target have. Once it becomes your speed, it becomes subject to Unarmored Movement.

Similar to Special Types of Movement in the PHB, page 182)

While climbing or swimming, each foot of movement costs 1 extra foot (2 extra feet in difficult terrain), unless a creature has a climbing or swimming speed.

Here, Swimming has a penalty, unless they have a Swimming Speed. Once they have that Speed, from whatever source, then Unarmored Movement should apply.

Rule of Cool

And it's fun! Monks are supposed to be super quick. Let them be super quick in all their speed!