I ordered a Lumia 1520. I need your help!

[Windows Central Question]

Hello, guys! I have been a windows phone user for 2 years and even with all the downsides I am still a fan of the platform. Yesterday I ordered a second-hand Lumia 1520 from an USA store. The phone is unlocked, but I have a few questions. Will I have problems with the WiFi, 3G, 4G standards of the phone since I will be using it in Romania (Eastern Europe)? Can you give me some advice on what else I should check when the phone arrives? Are there any quick to install apps that can give me info about the phone, so I can be sure everything is okay (time it has been used, dead pixels, a quick test for the hardware of the phone- camera, Bluetooth, flashlight, display, speaker, battery, touchscreen, microphone, vibration etc.) ? Any other tips and advice would be very useful! Thank you! Sorry if I am posting this in the wrong place, but its urgent.