Yes.
Yes, it should. That's the deal that was offered - so long as you have all the pre-LP content, regardless of how you purchased it, you'll get the LP.
In theory, it should be fine. They're currently working through a bunch of bugs to polish the game. I don't see why they wouldn't go back and fix the bugginess of the LP. I'm assuming that you mean there is bugginess with the LP - there are too many bugs with main game to expect all to be fixed, so I'd expect only the most game-impacting ones to get fixed.
On the other hand, this is a company that made a single line error and practically broke the game, and despite it only taking 5 seconds to fix, ignored it for well over a year and didn't even acknowledge it until now. I'd like to say that we could trust them to fix any bugs, but the cynic in me says that we have to treat them with the attitude of "believe it when we see it". The problem is probably that top brass wanted them to drop the game after NFP, and that's why we saw nothing about it. Someone probably got through to them that leaving the game as-is will damage the brand so this is an olive branch. That concerns me in terms of bug fixes because they still want to drop it - so if there are any bugs left at the end... it's probably tough. That relates to your question because it means we can't guarantee that everything will be fixed. That goes doubly because Aspyr handles Mac and let's just say I won't be buying any Aspyr games again because of their attitude towards the game.
In short...in theory it should be fixed...but I, personally, would hold the attitude of "I'll believe it when I see it".