Before going to the Hall of Echoes there are just the 2 merchants available in Aleroth.
If you want to farm extra experience points in the D2:ED section of the game, it would be better to do so in Keara's flying fortress than the ministry.
how to reach level 40+There are some places (like caves) in the FoV section of the game where enemies can respawn, and they give much more experience than the relatively weak opponents that you can get to respawn in D2:ED.
In the original release of D2:ED I delayed going to Aleroth (low thirties for level). In DKS I went as soon as I was able (though delayed going to Sentinel Island as long as possible, so was level 25 when I got to Aleroth) and just put off doing the ministry.
In DKS I tried maximizing my experience gain, put off turning in quests when possible, etc, but it really didn't make a significant difference by the end of the game. At the end of D2:ED I was a little under level 37, and in DKS at that point (with some changes to quest experience to make levelling faster at the start of the game, etc) I was a little over (I also played with the respawning opponents in the Maxos temple mirror room a bit).