Coconut water from the fruit, then scrape and eat the flesh
Beer - Yes, there is beer in Kota Bharu.
Go to the Chinese restaurants where beer is served to non-Muslims only.
There are a few watering holes in KB - one has a disco feel about it called Restoran, a few have a few "Thai drinks promoters".
However, if you are into coffee - look for cafes / kopitiams. Some have wi-fi facilities.Go to the riverside Pelangi Mall for a refreshing river view and freshly brewed coffee.