If you can connect to Facebook with those credentials then it should work in the game normally since it uses the Facebook login. What happens if you load the game directly from Facebook, does it load you where you were or is it loading you at level 1?
2295 is a timed level so it doesn't matter what score you reach, it's still possible to lose if a candy bomb blows. If one is about to blow and you can't stop it and have already hit the minimum score... don't do anything, just let the timer run down to 0 and you've passed.
Not sure, If you close the inbox that pops up at the start without accepting any gifted lives when you start you should have an envelope on the saga map where they are stored and redeem later. But yeah the downside to playing through browser is that if the game session is refreshed or reloaded, those messages are gone.
You can sync your progress to either Facebook or Kingdom. If you do, when you reconnect to that account in the game again from any device, the progress from the point where it was last synced will come up.