check the stickies
just as you are too lazy to read everything, i'm too lazy to tell you everything

"Can you get the White Lotus Headband after beating konquest, and what exactly does it do."
You can only get it before you get thrown in prison by Hotaru. It allows you to do the "Raiden's Staff" quest. Beat the "beast men", talk to Kung Lao, head to the ice cave in Outworld, then head back to Kung Lao.
"Where are the keys, or how do you go about unlocking all the secret characters."
Noob - Smoke Open Koffin DM using 3,642 Onyx Koins in Krypt
Jade Open Koffin OI using 2,417 Jade Koins in Krypt
Kenshi Found in a treasure chest on map C-3 In Earthrealm in Konquest
Havik Found in a treasure chest on map H-4 In Choasrealm in Konquest (check the houses)
Shujinko Finish Konquest Mode
Li Mei Find her in a house in outworld (Area F-7)
Raiden Defeat Him at Point E-3 in Orderrealm After Finishing Konquest Mode
Liu Kang Found in a treasure chest at point G-8 in Edenia at 12AM Friday Morning behind the tent After beating Konquest
Kira Found in a treasure chest at point H-2 in Earthrealm between 7-9pm
Tanya Found in a treasure chest at point A-3 in Outworld between 7-9pm
Sindel Found in a treasure chest at point D-1 in Netherrealm (1-4 am)
Hotaru Found in a treasure chest at point H-1 in Orderealm after 4AM
"What character has a 12 hit combo to use on Johnny Cage."
The best thing to do is unlock Shujinko's bicycle kick and spear and then spear Cage, pop-up in Mantis style with up+4, than hit him with the bicycle kick.
"Yes, I realize if I search the forums for a couple hours I can find the answers to all these questions, but, I do not have time to go through the hundreds of pointless threads and weed out the good, factual answers."
I know what you're talking about, that's why I'm glad to help here.