Baldur's Gate II Throne of Bhaal - 2001 VG was released on:

USA: 21 June 2001

Poland: 31 July 2001

Baldur's Gate plus expansion - Tales of the Sword Coast

Baldur's Gate 2: Shadows of Amn, plus expansion - Throne of Bhaal

Baldur's Gate: Dark Alliance,

Baldur's Gate: Dark Alliance 2.

I wouldn't say any of BG2's characters are secret, ie, they're all introduced to you during the course of the game's plot. However the expansion, Throne of Bhaal, gives a character who's a bit of a surprise, Sarevok, the player character's half-brother and the original Baldur's Gate antagonist.

Baldur's Gate happened in 1998.

Yes, that will work just fine.