Whatsapp has been giving me trouble for a while now. If I delete it fro my iPhone and reinstall it from the App Store, will I need to pay for it a second time?
Nope, if you already paid for the service you will not be asked to pay for it again (account is linked to your phone number)
last seen is not working
WhatsApp is awesome, just love it. It's better than Viber and iMessage.