Dota – Where do the DotA All Stars and DOTA2 announcer voices come from? (Ownage, Unstoppable, etc.)

There are virtually no differences. It's almost an exact copy of the original Warcraft 3 map, minus the improved graphics, down to the very level of the basic controls itself (animation cancelling, etc.).

The biggest difference that you'll feel while playing it is the matchmaking system which Dota2 will take from games like Team Fortress 2 and Left 4 Dead and a ranking system about which we don't know much yet.

I'd love to give sources on this, but I'm afraid I don't have ones on hand right now. There aren't exactly a ton of interviews on the game, and most of this stuff is gathered from simply watching the game (it looks like it's an exact copy) and posts by icefrog (one of the original Dota caretakers who now works on the game) on various forums.

Flesh heap stats are floored (rounded down) to the nearest integer. You cannot use in game text commands in the chatbox like in the original dota, however there is an icon for flesh heap that displays when you have a level in the ability. A flesh heap bonus of zero will not show.

There are icons for other heroes too, like Silencer's intelligence stolen, but I'm not sure what else you'd have in mind.