First question, is it safe to vape around the kids. I can't say for sure but I believe it would be more safe then the analogs. If you notice cigarette smoke tends to hang around forever, eventually if clings to your ceiling or curtains in your house. The vapor doesn't do that. I dissipates into the air. I tend to hold the vapor in my lungs and very little or no vapor is visible when I exhale.
I also notice a poster here, Ledford, has a bird. I believe most birds are sensitive to smoke. He does lots of reviews on youtube vaping like crazy around the bird. Maybe he or another bird owner will jump in.
As for using a different juice in your cartages. Once you get the thing you will find it is not hard. In the mouthpiece there is a small square of polyester. Use tweezers to pull it out and then rinse it, and the mouthpiece in warm water. Let it dry completely. Water gets trapped in the small crevices of of the mouthpiece so blow or tap on it. When it's all dry use the tweezers to put the polyester back in, drip the new liquid onto the polyester and your ready to go.
Edit to add-with the e-cig you wont get the smoky room effect. It just keeps disappearing no matter how much you puff.