1. Considering that XC skiing is pratically a religion over there, I imagine you should be able to rent both. Just keep in mind that to skate ski, you need trails that are groomed for it.
2. Unless you have skate skiing experience, and it sounds like you don't, stick with classic (trad). Skating requires a lot more techniqe and strength. Just try skate skiing uphill. On the other hand if you roller blade a lot, you probably have both, so give it a shot. If you can walk, you can most likely ski classic.
3. Who knows? waxless skis may be sacreligious over there, but I doubt it. Most rental skis are waxless, otherwise they would have to spend a lot of time & expense prepping them every time they were rented.
4. Waxable classic skis are the same construction as waxless classic skis, the only difference is the pattern. You can usually buy both a waxable and waxless version of most classic skis. There is a big difference between skate and classic skis. Skate skis are shorter, narrower and a lot stiffer. For skate skiing, the bindings have a ridge in the middle that runs the length of the boot , and the boot has a hollow that it fits in. So when your foot is flat on the ski you can exert a lot of sideways force.
Have a great time in Finny.
Just another Mike on Gunks.com