I don't cut cardstock, only the sticky vinyl or iron on vinyl. I have not changed my blades at all, and I have had it for maybe 4 years. I imagine it is a different story with cardstock, though. I have an extra blade on hand for when I feel its needed, you may want to keep a few extra on hand, though.
I have found that my computer runs a little lag-gy after using the Cricut program. so I sign out of the program and restart the computer every time i am done. probably not necessary, but I do it anyway.
There is certainly a lot that the Cricut can do that I have not explored. hopefully others on here will offer more information for you. Enjoy your new toy!