If I install all 4 of the BG games and start from the beginning by playing BG1 will I be able to use the BG2 features in the entire game play- for example the new characters, spells, exp levels, etc.? For example can I choses some of the new classes from BG2 to play BG 1? Does anyone know?

No, BG1 and BG2 are discreet games. Having BG2 installed will not affect BG1 in any way.

However, installing the BG1 expansion Tales of the Sword Coast will enhance BG1: it does not change the ending, but rather raises the XP cap, adds more spells, new items, and four new areas to the game. ToB is similar in that it adds new spells, weapons, armor, etc., to BG2. But as I understand it, you don't play the ToB modules until you have completed Shadows of Amn. Or? Not too long ago I had BG2/ToB installed and there was a distinct option on the start up screen for ToB, so that was my assumption. But please someone correct me if this is wrong.

<blockquote>quote:</font><hr>Originally posted by Lemernis:
But as I understand it, you don't play the ToB modules until you have completed Shadows of Amn. Or? Not too long ago I had BG2/ToB installed and there was a distinct option on the start up screen for ToB, so that was my assumption. But please someone correct me if this is wrong.<hr></blockquote>

You're right. The ToB areas come after the final battle of SoA, except for Watcher's Keep which can be entered from both SoA and ToB.

So basically you are saying that there is more than Watchers Keep to the ToB expansion. (I just started replaying BGII with ToB on board) These areas can still be accessed by starting a new game of BGII right? I mean you don't have to specifically click the ToB option upon load up do you, ALL the areas wil be in my SoA game not just Watchers Keep.

<blockquote>quote:</font><hr>Originally posted by The Dark:
So basically you are saying that there is more than Watchers Keep to the ToB expansion. (I just started replaying BGII with ToB on board) These areas can still be accessed by starting a new game of BGII right? I mean you don't have to specifically click the ToB option upon load up do you, ALL the areas wil be in my SoA game not just Watchers Keep.<hr></blockquote>

No the only ToB area you can access during SoA is Watcher's Keep. ToB provides a conclusion to the bhaalspawn saga, but that does not start until you do the final SoA battle, you will then be transported to a brand new area and start ToB. You also cannot access any SoA areas when you start ToB.