Those are great questions. We all picked it up somewhere....but no one knows for sure where.
C-diff is passed along through the fecal-oral route. You touch something that has a c-diff spore and you touch your face or some food and it goes into your system by way of your mouth.
For this reason, we constantly push hand washing. If you become aware of how often your hand goes to your mouth, you will see how easily any germ could enter your mouth. Putting on lipgloss, for instance. Licking your finger to then turn the page of a book....a bad habit of mine. You buy popcorn at the movies. How many things do you touch before you eat the popcorn? And so on.
My ID doctor told me that I would "shed spores" for 6 months after I was well. You only shed spores from one exit in your body....your bottom. However, if you don't wash those hands thoroughly, you can spread the spores around.
Surprisingly, I have never read about a family member catching c-diff at home. So, if you are careful about washing your hands, your friends should not catch it from you.
Once the spores are in the environment, they are quite strong aNd can live for months on surfaces. Only bleach will kill them so clean your bathroom with a bleach product.
I hope this helps. Good luck!