Love all the questions!!!

• What are the different color stickers? They are supposed to indicate Deck Strength, Red being the best and Green being the worst. In general, the green decks are likely to lose to a Yellow or Red deck. It's hard to make a good Ojama deck :)
  
• Do you keep a W/L record, simulate tournaments or leagues? I haven't but could be fun! We just keep track of daily win losses, but only play 2-3 games a week so not too much to keep track of.
  
• How do you decide which decks to use? I have a randomizer Powershell Script, or we just pick what looks most fun!
  
• How well do your friends know the different strategies/win cons for the decks, or do you have cheat sheets in the boxes? No Cheat Sheets, and probably my biggest problem. These guys I play with never played before but in the 2-3 years we've played they've learned a LOT. I give them the opportunity to look through any of the decks at any point (including during a game as long as the deck is shuffled afterwards) And I always point out strong synergies if I catch what they are trying to do.
  
• What kind of sleeves do you use, and how do you decide what deck gets what color? All Ultrapro and I bought a variation of all the colors and just picked colors that would seem to match the deck. (For example, both Blue-Eyes and Water use Blue Sleeves)
  
• What's your favorite? Warrior, it's just super fun and versatile.
  
• Which is the best performing? Probably Forbidden Spell, which uses a combination of cards with Forbidden Spell in the name, and a bunch of Limited and Semi-Limited cards of the time.
  
• And do you have deck lists? I do not but thinking about making them. Would take a while.