Your iPhone should continue to work normally on the Verizon data network if you don't sign into the WiFi. If you're wondering if your iPad will work from your phone's data that will depend on your data plan and if it includes a hotspot option (their newer capped plans do.) If you're not looking at a using it a whole lot a prepaid option may be your best route, provided you want a second device. Virgin (sprint) has a cheap $5 per day 250/mb plan, if you're not looking at heavy use.

What are you looking at doing with your hotspot?