Do give your cartoon character a challenge. Sonny goes cuckoo for Coco Puffs. The Trix Rabbit never gets to eat Trix. The Giecko cavemen never get the respect they want. What these challenges do is make the character more endearing. People empathize with them, and that forms a bond. How important is having an emotional bond with your customers?
Do have a professional cartoonist/graphic designer develop it for you. There are many fine nuances that go into a well-designed cartoon brand mascot. What looks good on the sketchpad may not look good when it's reduced down to fit on a business card. A cartoon brand mascot may need to look good on a computer screen, embroidered on a shirt, etched on a pen, printed on a business card or blown up on a billboard. A good designer knows how to use the proper line weights; colors and shading that reproduce and hold their integrity over a wide array of applications.
Free graphics get you halfway to what you need, whether it's for an announcement, flier, or website. You love your friend, but you don't have to wait on him. With free clip art as an option for your design needs, you always have a stopgap measure. You really might need that professional-looking site or flier, but you can at least fill the space until your buddy pulls through. After all, if you are willing to take the hit by taking a less-expensive professional design route from your friend, free clipart is the next, easy step down.