If I use free WiFi in a hotspot, can data be easily sniffed? If I use my mobile device in a Wifi hotspot, can I take it that it bears the same risks as using a laptop in that data can be easily sniffed and that the mobile device is also open to man-in-the-middle attacks?
Yes, you are subject to the same risks as you would have in a laptop (or any device that connects to a wireless network, for that matter); to avoid them, the standard security procedures apply: do not use unencrypted connections that you do not trust and always prefer HTTPS for browsing.