Spoilers: (Highlight to reveal)

Motaro apparently does have an Alt costume, which is Found/Unlocked in the Netherealm Cliffs area of Konquest. No pictures of it here, but this disproves people saying he didn't a few weeks ago.
One of the Relic Items to be found in Konquest mode is "Smoke's Cigarette." Har dee har har.
Another is Meat's Steak. They just keep on coming....
Pretty much all that's found for unlocking in Konquest is Relics, Alt Costumes, Music Files, and pieces of Elder God Armor (These Unlock something when you collect them all, but I haven't figured out what yet.) Everything else seems to be purchasable in The Vault.
There's actually a very extensive Ultimate MK3 guide included in the MKA armageddon guide... I have no idea why they did this, since UMK3 isn't even included in the regular version, but it's there, and it's nice.

Spoilers: (Highlight to reveal)
Nope.

Spoilers: (Highlight to reveal)
The only secret characters are Blaze, Taven, Daegon & Meat, and Ninja_Arts already said how to unlock them...
As far as I can tell it's one KaK per profile, but you can edit them as much as you want. (Don't wuote me on that, this thing is very hard to read, for as slow as it runs)
I have no idea how the dead guys like Rain and Shinnok came back, it only gives very vague general bios for each character. In fact, it doens't even acknowledge Shinnok dying, it just describes what happened in MK4, then says "He was defeated, and his current agenda is unknown." I'm guessing these aren't the ingame bios. I'd give you the ones that got asked for, but really for everyone who isn't a new character (Like Chameleon or Taven), they're just re-hashes of the Deadly Alliance and Deception Bios. (Hotaru's talks about tracking Sub-Zero, Hsu Hao's talks about infiltrating the Special Forces, etc...)
The Requested Moves:
Kung Lao:
Chest Kicks
Whirlwind Kicks
Hat Throw
Wind Teleport
Wind Teleport Hand Bash
Wind Teleport Fist Smash
Wind Teleport Face Kick
Wind Teleport Kick
Air Dive Kick
(Damn He Had a Lot... most based off his Wind Teleport)
Cyrax:
Armbreaker Throw
Detonator Close
Detonator Far
Funky Spin Kicks
Exploding Teleport
Slice and Dice

Spoilers: (Highlight to reveal)
I have no idea how many costumes everyone has. Each Bio doesn't list costumes, it just shows a few screenshots of each character fighting themself. Most (Not all) are of one wearing a main, one wearing an alt. Chameleon's however, has him fighting himself, both wearing mains, Thusly, I have no idea if Chameleon's Alt could be Khameleon, if he even has one.
Goro, Kintaro & Motaro definately have alts, though I'm not quite sure what Motaro's is... Moloch, Onaga & Blaze don't appear to, though anything is possible...
The layout isn't very good. Lots of text, lots of old re-used pictures. Very little new-hotness.
The lame Meat Bio is indeed the one printed in the guide, though I doubt that it's the final in-game bio.
There is nothing to indicate that Daegon is playable in konquest, as far as I can see...
Sonya is pictured in her MKDA Main and Alt, don't see any others
Taven Moves:
Gold Dragon Lock
Inner Fire
Ring of Hatred
Godly Charge
Speed of Light
Daegon Moves:
Evil Touch
Rolling Hatred
Rushing Shoulder
Cloak of Avoidance
Firey Hands
Read the names and judge for yourself. I can't tell from button commands and still pictures.

Spoilers: (Highlight to reveal)
Happy to hear Motaro has an alt, although am intrigued you can't tell what it is.