Flights: you have to get your flights from your country to Lima and them you need to take another flight to Cusco city. It is really easy because you can get all of this things by internet now and this is the airlines that come to Cusco (LATAM, Avianca and Taca). of course if you coming from Puno or another state of our country you can come by bus too.
How many days in Cusco before your trek: there aren't details about how many days that you should be in Cusco but as a personal experience in this area we suggest to come two days before your trek in order to acclimatize here and at the same time after you just arrive to our city we suggest to drink plenty coca tea and water. because, it´s gonna helping you so much for the following days.
Travel insurance: You won´t need it, but if you have one it can be good idea. However, one of the problems are the altitude and if you´ll come few days before to Cusco is gonna be good enough.
Vaccinations: This is not required for you. because, even the place that we´ll hike there aren´t any illness that you need vaccinations.
Tips: of course all of our staff have a salary and some another prize for the best staff in each of their areas. However, there are many of our customer that they really appreciate for the amazing job that this worker will do for you and you have the chance to give something to then that motivate too keep working with so much enthusiasm.