All the original style carts will work in all the Cricut models. The Imagine carts {which are smaller} work only in the Imagine and the E2 {the print carts won't but the art carts will}.

The only extended warranty I've seen have been from HSN and purchased with a specific time period of buying the machine.

Yes, the Lite carts will work in all the models!

They are called Lite because they have fewer images and creative features. Here's a little more info on the different carts:

The regular Cricut carts contain 6 full Creative Features and can hold up to 700 images. These carts come in the storage box and have a spiral bound handbook showing all the images.

Lite carts have one Creative Feature key for layers and have 50 base images, some with additional layer options using other keys. These carts come in a plastic storage box and have a tri-fold pamphlet showing the images.

There are also:
Solution carts contain 2 Feature keys (usually a Shadow and a Blackout), one layer option and hold 50 images (not counting shadow, blackout or layers). These carts (initially) had no storage box and all the images are shown of the cardboard packing.

Seasonal carts have no Creative Features but some images have layers or shadows that are on the Character keys and hold 30 images and are usually a limited edition and centered around a theme. These carts have no storage box and all the images are shown on the cardboard packaging.

Project and Event carts have fewer images than full carts, images centered around a theme but these not limited edition releases. These carts have a plastic storage box and a modified (because there aren't as many images), non-spiral bound handbook.

Cake carts are really full carts just with images geared toward cake decorating but they can also be used with papercrafting.

Then, there are the two categories of Imagine carts: one that is images and patterns (Art) or just patterns/colors (Colors and Patterns).

And now, there are digital carts for use with CCR or a Gypsy.

Edited by user Tuesday, January 22, 2013 8:26:45 PM(UTC)  | Reason: Not specified

Scrapalette is great for any info you need and always helps i think pc shoul look at her and the info she gives out to people and try to make the members board and customer service they give as good as scraplettes help .
KEEP UP THE GOOD WORK SCRAPALETTE WE DO All love your help .

You should go to the main forum, click on Cricut Community an then to Cricut chat, lots of information in there about the Circle.

Actually, click on the Cricut Circle name at the very top of the page. You can buy a membership with money on the shopping pages here on cricut.com or with reward points on cricutrewards.com.