Hi,

I'm not a Carrara user, but I think that the basic render you're after is certainly not difficult. It's just a matter of assigning a color to your object, creating a few lights (with or without shadows), maybe a ground and background.
Then you'll probably go to the render settings and tweak a few parameters and there it is. :-)
Basically, it's the same process in all applications.

For what concerns modeling, there's a big difference between MoI and Carrara, as MoI is a Nurbs modeler and Carrara is a polygonal modeler. Modeling techniques are quite different. I suggest you to browse this forum and maybe a Carrara forum (there's an active Carrara community at www.polyloop.net) to see the differences. As Frenchy mentions, Nurbs are more suited for hard surface models while poly modelers are good for organic modeling (well, not only that...). Nurbs modelers are very good for boolean operations and fillets.
As you mention you've some knowledge of 2D software, I will make a comparison (It's very simplistic, take it for what it is...) and say that you can compare MoI to a vector application (Illustrator) and polygonal modelers to bitmap application (Photoshop). At a certain moment, if you want to use your vector art in a bitmap application (that does not support vectors) you have to rasterize your art.
That's a bit what you do when you export your MoI object in a polygonal format (like OBJ) to render in a third application.

I think that most of us use more than one 3D application so there's no "problem" using MoI together with Carrara. It's a matter of personal choice. Some people prefer an "all in one" package (modeling, texturing, rendering and even animation) but these are usually more expensive. You just have to find the application(s) that work for YOU. (try demo versions)

MoI is easy to learn, simple to use but also incredibly powerful. And it's FUN ! Something really marvelous !