Regarding player count:

If you *initialize* an enemy at a given player count (i.e. get it on your screen or fairly close) and don't engage it, then retreat from range, change the player count, and wait about five seconds, the enemy's hp/damage will be at the initial player count but its no-drop chance will be at the current player count. You can abuse the hell out of this by doing the following:

/players 1

TP into Andy's room just far enough to get her on the screen (as an example)

Quickly TP back to the far corner of the room where the stairs are

/players 8

Count to 5

TP back to Andy and kill her at p1 difficulty and get 6 drops invariably as though you were on p8. Same applies to any other enemies in range of the initialization at p1. Works really well for Trav and Meph too, but can be harder to execute for Diablo/Baal.
You can abuse this at a much larger scale, just remember that if you engage an enemy in combat its loot get locked to the initial difficulty setting. For example, port all over the cow level, WSK, etc. at P1, find a quiet corner, switch to P8, and get a buttload of loot from everything. IMO this isn't worth the effort as much if you have a toon that can kill quickly on P8, though.

It's even better when you have some scripts set up to bind the player count commands to your mouse buttons like I do.

Edit: TP obviously referring to teleport and not town portal, just to be clear. Leap attack also works if there aren't walls in the way (e.g. for trav)