Take a cardigan for the evenings just in case. It’s usually cooler on the sea front than away from the beach.
Plenty of tavernas and cafes for lunch and dinner. Prices vary from under 5 euro for a gyros/kebab and a soft drink to 20 euros each for a meal including a couple of drinks in a nice taverna. There is something for all price ranges. Most bars do snacky lunches such as salads, sandwiches etc. My favourites in no particular order are Vlahos, Amos, Paralia Aeollos and Bakalis on the sea front and also Tsapari next to the Post Office. There is also a lovely Italian called Pomodoro on a side road up from the beach.
The beaches are mainly a mix of sand and shingle and pretty shallow. Sandier beaches are found towards Kalithea or towards Palliori in the other direction. If you find the pebbles underfoot uncomfortable getting in and out of the sea then swimming shoes are available for a few euro at most beachfront shops. I love mine! Most bars have sunbeds in front of them and the etiquette is buy a drink and the bed is free. Most beaches serve snacky food for lunch. The beaches can get busy in the centre but walk a hundred metres past the pier and you will find they are quieter.
Nightlife is around the many bars and tavernas. Paul’s Place in the old village square does a great English breakfast and their cocktails are very good! They also serve food. Behind Paul’s is Villa Elia. They have live music at the weekends and often the Greeks will get up and do Greek dancing which is lovely to watch. Other bars on the seafront worth a try are Menta and Cuccaredus. They are lively but not too loud! Mamos on the main road has been there years and is good for coffee or cocktails if the promenade gets a bit too lively.
There are boat excursions from the small pier in Pefkohori. Ask at the booth at the end of the pier. Most tour operators do excursions further afield such as the Mount Athos cruise which is a lovely day out. Buses run along the main road and there are timetables at the stop. It is worth visiting Afitos which is a traditional village with great views over the sea. And for a change it is worth spending some cash on a taxi to the next village Hanioti which has a lively square full of bars and tavernas and is great for shopping. The taxi rank in Pefkohori is on the main road opposite Mamos.
Shopping is mainly a mix of beach stuff and Greek souvenirs such as olive oil products, food stuff etc but there are also some nice clothing and shoe shops. There are plenty of bakeries and mini supermarkets dotted around. and a number of ATMs so getting cash won’t be a problem.
You can find more information at Kassandra attractions.
Have a great time.