Yup. Those could be anything.
GPRS connections can be user requested or app/publisher requested. I looked up whatsapp and this app sends push notifications. So if this app, or any app on his phone, sends push notifications then these will most likely show as GPRS connections. The GPRS connections could also be, for instance, an email app downloading his email or an automatic update.
WhatsApp - Wikipedia, the free encyclopedia
3 GPRS connections over 1 minute long can't be "anything."
Text only messages and email retrieval lasts a couple seconds, tops.
WhatsApp messages can be audio or video. I use WhatsApp daily. The only time it accesses messages for 1 minute or more is when audio messages are being sent back and forth. Or video.