This June, we will be traveling by car from Prague to the Tatras mountain area, to the small town of Matiasovce, to visit where my grandparents were born. Google maps says it's about a 6 1/2 hour trip but their recommendation to get there is through Poland, past Kracow, and enter Slovakia from the north. Not having done this trip before, should we expect any trouble at the borders going from the Czech Republic to Poland and then from Poland through to Slovakia. The entry point into Slovakia is near Spisske Stara Ves. Alos, I'm told that we need to get some sort of pass to travel on the Slovakia highways. Is that true and is that also the case for the Czech Republic and/or Poland?
Car rental companies always want to know in which countries you will drive, so do tell them. All three countries are part of the Schengen borders/visa agreement, so there should not be any border delays. Czech Rep and Slovakia each have highway tax stickers that may be already on the car or that you can buy at the border or a gas station. In Poland, faster expressways have tolls to pay as you go. Dropping a rental car in a different country adds to the rental price.
You will rent your car in Prague so it will almost certainly have freeway sticker for the Czech R. You will have to buy sticker for Poland and also for Slovakia. If you go just to Matiasovce then you won't need it because it is close to the border and you won't be using freeway to get to it.