I've had the watch for some months now, and it works great with Android! With 4.3 and up, use can dismiss notifications on the pebble and they will be dismissed on the phone as well (using Notification Center). I use it to set timers on the watch (using Simply Alarm Holo) and also recently I've using it to track sleep with the Sleep as Android integration. And the biggest attraction to me for it is that with PebbleTasker you can trigger any Taskeer task you have set up to do pretty much anything you can think on your phone.
I've been using the app for about a year and a half by now and it's been really great as an alarm (it detects and wakes you during light sleep). Plus it calculates sleep duration, which you could use in your app. I believe that the data are accessible as a .csv in the phone's SD card so it shouldn't be too difficult.
Latvia has been a member of the EU since 2004 (which entails all you mention), and now it joined the Eurozone as well, and will use euro as its currency.
About blocking the Youtube notification for account merge: add this custom filter in Adblock ||s.ytimg.com/yts/jsbin/www-linkgplusdialog* and it stops the pop-ups. Someone posted this a while back on Reddit, and it actually works really well.