Create characters and illustrations for mobile game

I have the full source code of a bubble shooter game And I want to reskin the graphics so instead of the cats/pet characters, I want to make little cute monsters that are the main characters. I will provide link to our game and existing graphics so that you know exactly what needs to be redesigned. We want characters to be appealing both to male and females. And we have thought about using a bubble monster theme but we are open to your suggestions as well specially if you are experts designing a certain type of character and think that they would be suitable for this bubble shooter game. The idea is to develop 3 characters/monsters and give them human expressions: 1) unique expression of monster, 2) ecstatic (very happy), 3) surprised or embarassed (when the character loses the game). These are just suggestions and you can choose different expressions for each character if you wish. We wish the monsters to be fun/funny and to have human expressions so that our players can better relate to them and feel more engaged/entertained when they play. The characters are to be the starting point for the design of the remaining graphic design elements in the game (background,bubbles, game's name letters,etc) Im open to your suggestions and to collaborate with you providing you with feedabck through out the process, as I am a creative person myself. I see this process taking at least three stages and would be helpful if you can provide a price quote for your service braking down the different stages as for example shown below: 1) proposed sketch/illustration of three characters (concept is most important) 2) full development of characters and other graphic design elements (background,bubbles,game's name letters,etc) 3) Development of marketing material for google store/apple store Thank you