Home portals in the end have now (in 1.4.1 update) the same abilities as the nether portals, they will transport loots and mobs to other sides. So what might have happen was that when you pushed the egg with a piston it falled through the home portal and went in your overworld! Therefore it's probably not a bug. 🙂 I Hope I've helped you
Yes, the items might also fall below placed blocks..
I heard, from one of docm's videos, that you need to splash potions in front of you head in order to have the full effect. But that only apply to splash potion though.