1) Yes, you can purchase the device for full price from Verizon. You would have to come to the USA to purchase it, since Verizon won't ship outside the USA.
2) The Verizon unit is a CDMA & LTE unit with support for global roaming on GSM/HSPA. It's "unlocked" from a GSM perspective (you can put any Micro-SIM you want into it and it will work), but I'd think twice about importing a CDMA device with a GSM roaming radio into Europe as a primary phone for use only on GSM. There's no guarantee that it will support full-speed data on your network, or that you won't run into odd behaviors, as it's designed to be a device principally for use on CDMA and LTE. It's also uncertain if it supports the primary band of your carrier (CDMA phones with GSM roaming often only support voice and EDGE in many countries due to antenna and radio constraints).
3) Your warranty would only be valid through Verizon USA and HTC USA. You'd have to send it back to them, and it's unlikely that Verizon or HTC would support a CDMA device with roaming radio as a GSM-only phone... if you had any issues, you'd be on your own. Even if they would service your phone remotely, they wouldn't pay for shipping back to Europe -- you'd likely have to pay them extra for that, or pick up the device in person.
There's also the issue of Verizon's charging tech NOT being Qi, but a different proprietary Verizon standard for 110 volt USA wiring. I'm not even aware if it supports 220 volt mains or not.
I'd strongly recommend just buying the local-market device for your geography, unless you're willing to deal with the risks involved. Seems to me to be a lot of headache.