It sounds like you should be in pretty decent shape.
You can download GIMP for free, and use it to color your artwork. You can then use Illustrator to create word balloons and effects. Some good tutorials can be found here:
http://www.balloontales.com/tips/index.htmlThe most difficult part is going to be figuring out how to use GIMP to do the coloring since pretty much all tutorials talk about Photoshop. It shouldn't be too much different though. I wouldn't worry too much about versions and fancy new features, 10 years ago, me and some friends experimented (successfully) with coloring and lettering comics with Photoshop 3 and Illustrator 5.5. One of us even ended up coloring professionally for a while using PS3. And all of that was done on PowerMac 7500s. The only thing that will be a slight pain is dealing with the Classic environment.
Comic life looks like it might work pretty well (I'm downloading it now to try it out). If the balloon and effects are adequate you could probably just color the artwork with GIMP and use the Blambot fonts directly in Comic Life. You'd have more control with Illustrator, but ease-of-use may beat it out.
Good luck with the comics! You'll have to update us how it's going.