Drawing the Cards

How do I plan to randomize the chances of characters transforming and/or gaining powers? Here is my plan:

Draw the Cards
Each player will Draw up to 7 cards, stopping only if they get second Ace or they reach 7 cards, they then show what they drew to the GM. The meaning of the cards they draw are as follows:

1. Jokers Arcane powers, draw an extra card
Red card means Spell Caster (Heart means Shaman, Diamond means Mage)
Black card means Wild Card (Roll D20 to see what power they get)

2. Drawing the Ace (Aces mean transforming)
Spades: Elf (Agility increase of 1 Dice type up to 10, Low Light vision)
Hearts: Dwarf (Vigor increase of 1 Dice type up to 10, Low Light vision, Slow Pace)
Diamond: Ork (Strength increase of 1 Dice type up to 10, Infra Red vision)
Club: Ogre (Strength increase of 1 dice type up to 12, Toughness +2, Smarts drops 1 Dice Type, Ugly)

This means there is a decent chance multiple members of the party will either transform or gain a power or both. I prefer doing it this way for 2 reasons: role playing chances and because the world I will be running isn't like anything else they know so letting them pick a character type or race before hand wouldn't be fair.

I think it will be fun and interesting to see some of the members of this group to be forced to deal with their character waking up and finding out they are a Troll or Dwarf or one of the other races. How they and the other party members deal with that should be interesting.

One of the reasons I am putting all this work into this world is because I want to do something different. And one of my goals is to have the group slowly learn and react to this new world as strangers rather than knowing what is going on. So if I gave them the chance ahead of time to be an Ork with the Super power to become invisible would negate the novelty factor.