All over Peru, tips are very well welcome; it's not an obligation but mandatory in restaurants, bars, touristic and guiding services. It depends on your complete satisfaction service that professionals will provide you in all your visit to Perú.
The hotel is excellent well distributed in all cities, including A&Bthat, which are good options for someone who wants privacy and home attention.
Transportation like taxis, uber or local ones, is an option, but not so safe sometimes.
About whether in the coastal area, in summer ( Dec to Mar) it's warm enough, but on the contrary in the highland like Cusco or Puno and in the jungle too, it's rainy. Our winter is so wet (between May to Oct) in the highlands, its warmer; you know this phenomenon for the ANDES location and the coastal winds in front of them.